Global population growth peaked six decades ago

The chart shows how much people rely on rail versus road transport in 2021. The data comes from the OECD, and we recently updated our charts with the latest release.

Japan stands out with 28% of passenger kilometers traveled by rail. This contrasts sharply with New Zealand and the United States, where rail accounts for only 1.4% and 0.25% of passenger kilometers, respectively.

In Western European countries, rail transport is still in the minority, but less so. In France, 10% of passenger kilometers are traveled by rail, 6.4% in Germany, and 5% in the United Kingdom.

Countries with well-developed rail networks and high usage also tend to have lower domestic transport-related CO2 emissions.

Explore passenger kilometers traveled by road and rail in other countries →

Infant mortality rates have plummeted over the last 50 years. Globally, they’ve fallen by over two-thirds, from around 10% in 1974 to less than 3% today.

A recent study — published in The Lancet by Andrew Shattock and an international team of researchers — estimates that increased access to crucial vaccines has reduced infant mortality by 40%.

The chart shows the actual reduction in infant mortality rates with vaccination (in blue) and the researchers’ estimates for a hypothetical scenario in which vaccines wouldn’t have been rolled out (in red).

Based on these figures, vaccines are estimated to have saved 150 million children over the last 50 years.

Read our article on the role of vaccination in reducing infant mortality →

The chart shows that the average worker in wealthy countries now works only about half as many hours per year as in the late 19th century.

Based on data from economic historians Michael Huberman and Chris Minns, the average worker used to work between 2,700 and 3,500 hours per year, which is about 50 to 70 hours each week.

Recently, using data from the Penn World Table, workers worked about half that amount, between 1,300 and 1,800 hours a year, or about 25 to 35 hours a week.

This decrease has come from working fewer hours each day, fewer days each week, and fewer weeks each year.

Read more in our article on whether we are working more than ever →

Four decades ago, when HIV was first identified, it was an invariably fatal disease: nearly 100% of those infected died, typically within a few years.

The virus spread rapidly around the world — especially in Africa, where almost two million were dying every year by the millennium.

Thankfully, medical advances and global public health efforts have entirely changed this course. Modern antiretroviral therapy is very effective in both treating HIV — returning people with HIV to near-normal life expectancy — and preventing the virus from spreading to others.

The chart above shows this impact based on data from UNAIDS. Over a million people's lives are now saved by antiretroviral therapy each year.

Recent medical advances could take this progress even further.

Read more on how antiretroviral therapy has changed the lives of people with HIV →

Cereals, roots, and tuber crops — such as cassava or potatoes — are some of the cheapest options for getting enough calories. In poorer countries, people get much of their daily energy from these crops.

The chart shows the share of calories that the average person gets from these staples, measured against gross domestic product (GDP) per capita. This data comes from the Food and Agriculture Organization of the United Nations and the World Bank.

People in some of the world’s poorest countries get two-thirds to three-quarters of their calories from cereals and other staples, compared to around one-third in the richest countries.

This means those on low incomes have less diverse diets and often miss out on key nutrients from legumes, fruit and vegetables, meat and dairy, and other foods.

Explore the data →

Generative AI is a type of artificial intelligence that can create various media, including text, images, and music. It learns from existing data to generate novel outputs. Examples include language models like GPT-4 and Claude, which can write essays or answer questions, and image generation models like Midjourney and DALL·E, which can create artwork based on textual descriptions.

In 2023, funding for generative AI soared to $22.4 billion, nearly nine times more than in 2022 and about 25 times the amount from 2019. This surge occurred despite overall investment in AI declining since its 2021 peak.

The data is produced by Quid and made available through the AI Index Report. Quid analyzes investment data from over 8 million companies, using natural language processing to uncover patterns and insights from vast datasets. We have recently updated our charts on Our World in Data with the report's latest edition.

Read more on how investment in AI has been changing over time here →

This chart shows the gender breakdown of people affected by homelessness.

In most countries, men tend to be more likely to experience homelessness than women. In many, women make up 20% to 40% of the homeless population.

But this ratio varies a lot by country. In Colombia and Costa Rica, men are much more likely to be affected by homelessness, with only around one in ten being women.

In the United Kingdom and New Zealand, it’s even the opposite: more women experience homelessness than men.

This data comes from the OECD’s Affordable Housing Database and only includes countries that count people experiencing homelessness on a single night of the year.

Explore our updated and expanded topic page on homelessness →