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Guinea worm is an incredibly painful and debilitating disease; one that’s hard to imagine unless you’ve seen someone suffer from it.

As we explain in a dedicated article, it’s caused by the guinea worm parasite, whose larvae can be found in stagnant water. Drinking contaminated water lets the larvae enter the stomach and intestines. These grow into adult worms, getting into their joints and causing arthritic conditions, before emerging painfully through the skin.

The good news is that the world is extremely close to eradicating this disease. In 1989, more than 890,000 human cases were recorded globally, compared to only 15 in 2024.

As you can see in the map, these cases were recorded in just two countries: Chad and South Sudan.

There are three other countries — Ethiopia, Angola, and Mali — where guinea worm is still endemic (meaning it’s still considered present there), but they reported no new cases in 2024.

Here, we focus on guinea worm cases in humans, but it’s important to note that other animals — such as domestic dogs — can also be infected. This adds further challenges to eradicating the disease completely.

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Large families used to be the norm in Colombia, but that has changed a lot over just a few generations. I come from Colombia, and my own family reflects this: my grandmother had eleven siblings, my mother had seven, and I have just one sister.

My family is one example of this broader shift within Colombia. In 1950, around the time my mother was born, the fertility rate was 6.4 births per woman. By 2023, it had fallen to 1.6.

That’s what the chart here shows. It plots the total fertility rate: the average number of children a woman would have over her lifetime, if she experienced the observed birth rates of women in her country in the corresponding year. It’s the most widely used measure to track birth patterns across countries and over time.

The chart shows that Colombia’s fertility rate is similar to that of richer countries like France and the UK. It also displays Colombia’s trend alongside China’s for comparison. Perhaps surprisingly, the slope (i.e., the speed) of Colombia’s drop has been similar to China's, despite the latter introducing a one-child policy.

Colombia’s experience mirrors a wider change across many middle-income countries, including much of Latin America. Education of women, urbanization, declining infant mortality, family planning, and changing norms are all key drivers of this trend.

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If you ask people about whether the world as a whole is getting better or worse, most people say the latter. People are generally pessimistic about global or societal progress.

But they are typically much more optimistic about improvements in their own lives.

In the chart, you can see what share of people think they would be higher or lower on the “Cantril Ladder” five years in the future. The “Cantril Ladder” asks people to rate their lives on a scale from 0 (the worst possible life) to 10 (the best). Here, respondents were asked to rate where they are now, and where they think they’d be in five years.

As you can see, most people say they will be higher on the ladder across a wide range of countries. They expect their lives to improve.

Of course, this is not true of everyone, everywhere, but these results tend to support the argument that people are generally “individually optimistic, but societally pessimistic”.

Explore more data on happiness and life satisfaction across the world →

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Where you are born and stay for much of your life is a strong predictor of how long you’re likely to live. The chart shows the differences in period life expectancy across continents.

Average life expectancy has converged to a fairly narrow band between 75 and 80 years in North America, Oceania, Europe, Latin America, and Asia. Africa stands out: its average life expectancy is 64 years, over a decade lower than any other region.

This gap reflects several overlapping factors: high rates of child and maternal deaths, a heavy burden of infectious diseases such as malaria, HIV/AIDS, and tuberculosis, limited access to quality healthcare and infrastructure, and high levels of poverty.

Despite this, life expectancy in Africa has risen by almost two decades since 1974.

Explore life expectancy for individual countries →

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As this chart shows, two centuries ago, about one in three children in Sweden died before they were five years old.

Since then, the child mortality rate in Sweden has declined to 0.3%.

South Korea achieved a similar reduction much faster. This is often the case: the first countries to improve living conditions usually needed much longer than some of those countries catching up later — the latter can learn from what worked elsewhere.

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As someone born and living in the United Kingdom, one thing I notice when visiting other countries in Western Europe is how much more common smoking is elsewhere.

This is not just my imagination; this anecdotal evidence is backed up by the data on smoking rates.

In the chart, you can see the share of adults who say they currently use tobacco products (mostly cigarettes, but chewing tobacco is also included) across a range of countries in Western Europe.

The differences are large. In France and Greece, around one-third of adults use tobacco, more than twice the rate in countries like Denmark, the UK, and Norway.

Given that smoking is one of the leading risk factors for disease burden and premature death, these differences matter a lot for public health.

Explore how smoking rates compare in other parts of the world →

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Electricity access in Bangladesh has transformed over my lifetime: from around 15% of the population 30 years ago, to 99% today.

But progress on clean cooking fuels has lagged far behind. Fewer than 30% of households cook with gas, electricity, or improved stoves; most still rely on wood, crop waste, or straw. The chart shows that clean fuel usage is well below the levels reached by its Asian neighbors.

The costs are huge. Using biomass for cooking damages forests and harms health because people breathe in smoke and particulates. In Bangladesh, deaths from indoor air pollution are higher than the average in low-income countries, even though those countries usually have worse overall health. Indoor air pollution is close to being the country’s largest risk factor for early death.

Why has progress been so slow? The main barrier is economic. Bangladesh produces very little liquefied petroleum gas (LPG), relying instead on volatile imports. Its lack of domestic distribution networks also pushes prices, making clean cooking fuels expensive for consumers. Some of Bangladesh’s neighbors — like India — have given subsidies to help households switch; Bangladesh has not, making clean cooking fuels less affordable.

Cultural factors also matter. Biomass is often seen as “free” and convenient, and families are used to traditional cookstoves and the flavors they generate. They might be unaware of how damaging this pollution is to their health and skeptical of the damage that alternatives such as LPG could do.

Read my colleague Max Roser’s article — “The world’s energy problem” — for a global perspective on this issue →

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At the turn of the millennium, France had one of the lowest-carbon electricity grids in Europe (and the world). While countries like the UK and Germany emitted well over 500 grams of CO₂ per kilowatt-hour of electricity, France emitted just 80 grams — six times less. This was mostly thanks to nuclear power.

In the 1980s and 1990s, France rapidly expanded its power grid, and almost all of this growth came from new nuclear plants. The chart shows this: in the 1980s alone, nuclear power grew from 60 to over 300 terawatt-hours.

By 2000, nuclear power supplied almost 80% of the country’s electricity, making it much cleaner than its neighbors, mostly relying on coal and gas.

France still has one of the cleanest grids in Europe, although it has added very little nuclear power in the 21st century. It has opened just one plant in the last 25 years, in Flamanville, following long delays and cost overruns.

In the last decade, solar and wind power have grown the most.

See what countries produce nuclear energy, and how their generation has changed over time →

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The Northern White rhino is on the brink of extinction. In the chart, you can see the collapse of this beautiful animal's population as a result of poaching, habitat loss, and conflict.

Now, only two individuals are left — Najin and her daughter, Fatu. Without males, the subspecies is “functionally extinct” and cannot rebuild its population naturally.

Scientists, though, offer some hope of bringing the rhino back through assisted reproduction. Eggs from Najin and Fatu have been fertilized with preserved sperm from dead male rhinos to produce viable embryos. Since neither Najin nor Fatu can carry a pregnancy, the plan is to use a female Southern White rhino — the closest subspecies — as a surrogate, to carry the embryo through to birth.

In 2023, a surrogate called Curra became pregnant, showing that the method works. Sadly, she died of a bacterial infection during pregnancy.

Scientists plan to try again and are also exploring other breakthrough reproduction treatments to save the Northern White rhino before it’s lost forever.

Read my article on why large mammals are so threatened with extinction →

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One of humanity’s biggest victories has been the fight against infectious diseases. This battle has led to plummeting rates of child and maternal mortality and dramatically increased life expectancy.

However, there are still large differences in infectious disease rates between different parts of the world. As we might expect, deaths are much less common in high-income countries where almost everyone can access clean water, sanitation, and medication.

One common misconception is that this prosperity has come at the cost of an increase in death rates from chronic diseases, such as heart disease and cancers (collectively called “non-communicable diseases”). But this is not the case. As you can see in the chart, death rates from these diseases are also lower in richer countries. It’s not the case that we’ve simply substituted one health problem for another.

That means that the risk of someone of a given age dying from any cause each year tends to decrease as countries get richer.

Explore more of our data on causes of death across the world →

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The first nationwide law allowing same-sex couples to marry was passed in the Netherlands in 2001. Amsterdam’s mayor, Job Cohen, officiated the first couples. Twenty-five years on, these rights to same-sex marriage now cover 1.5 billion people worldwide.

These people live in 39 countries with marriage equality, mainly across Western Europe and the Americas.

This change in marriage laws has made a huge difference to the lives of many. But they are still in the minority globally. Four in five people still live in countries where same-sex couples are not equal under the law.

Explore which countries have legalized same-sex marriage →

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Over the last three decades, employment has changed dramatically across Asia.

In the early 1990s, almost two-thirds of the labor force in South Asia was employed in agriculture, and more than half in East Asia. Today, this is just 40% in the former, and one-quarter in the latter.

The chart shows the change across several countries in these regions. The share has fallen in all of them, but some stand out as having particularly dramatic transitions away from farming.

In Bangladesh and Vietnam, rates have fallen from around 70% to 38%. In China, they have dropped from 60% to 25%. In India, things have moved more slowly.

This matters for people still working in agriculture and those who have moved to jobs in other sectors. Productivity gains — which can allow family members and former workers to move away from the farm — mean that the financial returns per farm worker have increased over this time. Those who have moved to jobs in industry and services often see an increase in their wages. The result is that mean incomes have increased across these countries.

Read our data insight on this transition in today’s rich countries →

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Honest elections matter because they give people a say in how their country is run. They help ensure that governments reflect the people's will and that policies respond to real needs.

It’s sometimes assumed that support for democracy and fair elections is limited to particular regions or cultures. However, data from the Integrated Values Surveys, which asks people across many countries how much honest elections matter to them, shows otherwise.

Across all the countries surveyed, large majorities said honest elections are important in their lives. Nearly everyone said so in Indonesia, South Korea, and the UK. Even in countries where experts judge elections as unfree or unfair — like Iran, Egypt, or Russia — around 80% to 90% still said they matter.

In some contexts, people may feel pressure to answer this question in a certain way, either downplaying or overstating the importance of elections. Still, the consistency of results across such different countries suggests the demand is real.

Explore more data on free and fair elections for all countries →

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After only two years, California’s driverless taxis now transport passengers for more than four million miles per month. Although they still make up only a fraction of taxi trips in the state, they are expanding quickly.

This chart shows the monthly distance traveled in driverless trips in California. It measures the total number of passenger-miles, summing up the distance traveled by all passengers.

In August 2023, California regulators fully approved self-driving taxi services in San Francisco for companies Cruise and Waymo. However, Cruise stopped operating in late 2023 due to safety and regulatory issues, so the recent growth reflects only Waymo’s service.

Trips stayed under half a million miles per month until mid-2024. But since then, growth has taken off. Within a year, usage multiplied eightfold, climbing past four million miles by May 2025, the latest data available.

This is a new chart on Our World in Data — we will update it every quarter based on the latest reports →

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Since the 1960s, China’s population has more than doubled. Despite having more than twice as many mouths to feed, the amount of food it produces per person has increased dramatically.

Better seeds, irrigation, pest management, and improved farming techniques have all helped increase the country’s agricultural productivity. But the addition of nutrients through fertilizers has also made a huge difference. The chart shows the rapid uptake of fertilizers in China from the 1960s through the early 2000s.

While fertilizers can play a crucial role in feeding more people and using less land, they also have negative environmental impacts. Excess nutrients run off into rivers and pollute coastlines, and fertilizers can emit nitrogen oxide, a powerful greenhouse gas. Using fertilizers more efficiently helps grow food while cutting pollution.

China has made important progress on this in the last decade. As you can see in the chart, its fertilizer use peaked in 2014 and has fallen since then. At the same time, the country’s agricultural production has continued to increase.

In 2015, China launched its “Zero-Growth Action Plan for Fertilizer”, and its government policies have played an essential role in this turnaround.

Subsidies previously made fertilizers very cheap in China, which encouraged farmers to overuse them. Cutting these subsidies while offering incentives for agricultural machinery, precision technologies, farmer education, and larger farms (which tend to use less fertilizer per hectare) has made China’s farming sector much more efficient.

Read more in my article “How effective are policies in reducing the environmental impacts of agriculture?” →

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To track progress towards ending extreme poverty, the United Nations relies on World Bank estimates of the number of people living below a poverty threshold called the “International Poverty Line” (IPL).

In June 2025, the World Bank announced a major change to this line, raising it significantly, from $2.15 to $3 per day. As a result, 125 million people who would not have been counted as extremely poor before June are now included.

The increased IPL and the higher poverty estimates are due to a mix of overlapping changes, which we explained in a recent article.

Two things are particularly important to know.

First, the higher estimates of extreme poverty reflect a higher poverty threshold, not that the world is poorer. In fact, the latest data shows that incomes among the world’s poorest are actually higher than previously estimated.

Second, the overall message is the same whether we look at the new or previous estimates. Progress in recent decades has been enormous: well over a billion people have escaped extreme poverty since 1990. But this progress has now stalled. Incomes are stagnant in the places where most of the world’s poorest live. Unless this changes, hundreds of millions of people will be stuck in extreme poverty for years to come.

Read our complete explainer on the new International Poverty Line and World Bank poverty data →

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One of the most tragic beginnings in life for a child is to lose their mother during childbirth.

This was incredibly common in the past, and it still is in many countries today. But the world has made much progress in reducing maternal mortality rates.

As the chart shows, maternal deaths per 100,000 live births have fallen by 57% since 1985. Progress was temporarily reversed during the COVID-19 pandemic, but rates have started to fall again since then.

As a result, there are around 365,000 fewer maternal deaths each year than in 1985.

There are still huge gaps in maternal mortality rates across the world; we estimate that closing these gaps could save an additional 275,000 women each year.

Explore data for countries across the world in our newly updated data on maternal mortality →

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Few health problems affect billions of people at any time; anemia is one of them.

Anemia is a condition in which someone has fewer red blood cells or lower hemoglobin levels in their blood. It might seem like a minor health condition, but it can have serious implications. In children, it can lead to delays in cognitive and physical development. During pregnancy, it can increase the risk of mortality for both the baby and the mother.

Around half to two-thirds of cases are caused by nutritional deficiencies, particularly iron, but also folic acid and vitamin B₁₂.

As you can see in the chart, anemia is more common in lower-income countries: the condition affects more than half of children and almost half of pregnant women. Poverty often means that people can’t afford diverse diets and are more likely to fall ill from infectious diseases, increasing their nutrient requirements.

While rates are much lower in rich countries, it’s not a solved problem. I know relatives and friends in the United Kingdom who have struggled with anemia.

Read more in my article “Billions of people suffer from anemia, but there are cheap ways to reduce this” →

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This chart tracks the UN’s latest demographic projections for four large populations: India, China, Europe, and the United States. Together, they account for about half of today’s world population.

The curves are shaped by what the UN expects to happen to future fertility, life expectancy, and migration worldwide.

India and China are the world’s most populous countries today, and the UN projects that both will remain at the top through the end of the century. Yet their trajectories diverge sharply in these projections.

China’s population has already begun to fall and is projected to more than halve to around 630 million by 2100. India, by contrast, is expected to keep growing for nearly four more decades, reaching about 1.7 billion people in 2060 and gradually declining to around 1.5 billion.

In contrast, the United States and Europe are projected to change more gradually. The US is expected to grow slowly and steadily, reaching about 420 million people by the end of the century. Europe’s population, meanwhile, is projected to decline. Based on these figures, its population peaked around 750 million in 2020, and is expected to fall to about 590 million by 2100, not far from China’s projected level.

The UN’s model is the most widely used baseline for international population comparisons, but all population projections are sensitive to the underlying assumptions. Other research groups use different demographic assumptions about fertility, life expectancy, and migration to reach different long-term population figures.

Explore the UN projections in our Population & Demography Explorer, or compare them with alternative scenarios in the Wittgenstein Centre Human Capital Data Explorer →

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The Global Wildfire Information System (GWIS) has published weekly data on the area burned by wildfires since 2012. At the beginning of August, Spain was on track for a relatively low year. Its running total for 2025 was below the average and far below former records.

But just two weeks later, it had overtaken all of these previous years. You can see this in the chart, which shows the cumulative wildfire burn across each year. Large outbreaks in mid-August meant the last record, set in 2022, was rapidly surpassed.

This global dataset from GWIS only dates back to 2012, so it is a relatively short record. However, the European Forest Fire Information System, based on data starting in 2006, also found that this year’s fires were the highest in two decades in Spain.

Portugal has also seen extremely large fires this year.

Note that consistent data is unavailable over longer periods, so it’s hard to give context to the scale of these fires compared to the more distant past.

See how large wildfires in your country have been compared to previous years →