This chart shows the share of people who consider friendships “very important” in their lives.

There are clear differences between countries: Northern Ireland (70%) and Sweden (65%) rank highest, and the United States (51%) and Indonesia (42%) are near the middle. In comparison, in Peru (17%) and Myanmar (12%), smaller shares of the population say that friendship is very important to them.

These differences suggest that the value people assign to different relationships varies significantly across cultures. In some societies, friendships might hold a central role in everyday life, whereas in others, people might place greater importance on family, work, or personal independence.

It's worth keeping in mind that such surveys don't only capture people's different views on friendship but also how they communicate their views when asked in surveys. For example, in some countries, people might be quicker to call something very important than in others.

Explore more data on the importance of friendships →

Rich countries spend, on average, the equivalent of $6,200 per person on healthcare. This includes public and private expenditures.

In low-income countries, the equivalent expenditure is only around $100 per person on average.

This is based on spending data from the World Health Organization’s Global Health Observatory, which you can see in the chart across levels of income.

That means rich countries spend 60 times as much on healthcare per person as the poorest countries. Therefore, it’s unsurprising that life expectancy and other essential health outcomes are far worse in low-income countries.

Explore more data and research on healthcare spending and outcomes →

Certain pathogens, like viruses and bacteria, can cause long-term inflammation or directly damage DNA in ways that eventually lead to cancer.

For example, hepatitis B and C viruses are key drivers of liver cancer. Some types of the human papillomavirus are responsible for cervical cancer. The bacterium H. pylori can cause stomach ulcers and cancers.

The International Agency for Research on Cancer estimates that around 13% of cancers overall are directly caused by infections, as the chart shows.

For some cancer types, they estimate that infections cause nearly all cases. They’re listed at the top of the chart and include cervical cancer, adult T-cell leukemia and lymphoma, and non-cardia stomach cancer.

This is an area where prevention can be very powerful: by tackling the infections that cause them, we can stop these cancers before they start.

Vaccines for human papillomavirus and hepatitis B have already been developed and have lowered cancer rates in younger generations. Additionally, antibiotics for H. pylori, antiviral treatments, and improved hygiene can dramatically reduce the risks of other infections.

I recently wrote an article about the virus that causes cervical cancer and how vaccines can eliminate it. You can read it here →

There are considerable differences in access to healthcare across the world.

Rich countries have around ten times as many doctors per person as poor countries. You can see this in this chart, which shows the number of medical doctors per 1,000 people in a population. This includes generalist physicians as well as specialists.

The global average is around 1.7 doctors per 1,000. In low-income countries, the figure is around five times lower.

Explore more data on healthcare spending and access →

Homicide rates measure the number of intentional, illegal killings per 100,000 people annually.

Since 2000, rates in the United States have fluctuated around 6 homicides per 100,000. They fell from a peak of 6.7 in 2001 to 4.4 in 2014 but climbed back to 6.4 in 2022. Preliminary data suggests they fell back to 5.7 in 2023.

Over the same period, Europe’s rates fell from nearly 8 per 100,000 people in 2000 to just above 2 — a drop of almost three-quarters.

Explore homicide rates in many more countries →

In some countries such as Japan, the United States, or South Korea, almost all households have air conditioning in their homes. In others, almost none do. This includes countries like India or South Africa where extreme heat is frequent.

In this chart, you can see the share of households that had air conditioning (AC) in 2018. This data comes from the International Energy Agency.

Paying for the upfront cost of an AC unit is a key barrier to adoption, so as incomes rise, more people get access to them.

Access to air conditioning is becoming increasingly important as the world warms and extreme heat becomes more common.

Read more about how populations can protect themselves against extreme heat →

Cancer death rates rise steeply with age.

The chart shows this for a wide range of cancers, including bladder, breast, colorectal, stomach, and prostate cancer. The data comes from the United States Centers for Disease Control and Prevention.

Long-term exposure to risk factors — such as smoking, radiation, and certain infections — damages our cells. This damage accumulates with age, increasing the chances of cancerous mutations. In addition, our cells’ ability to repair this damage also weakens, allowing the mutations to accumulate.

Cervical cancer has a slightly different shape: its risks rise at a much younger age and then slow down. This is because it is caused by the human papillomavirus (HPV), typically spread through sexual contact at younger ages. Without HPV, it’s very rare for this cancer to develop, and infection can be prevented with early vaccination.

Read more about the risks of cancer with age →