Half the population of the Central African Republic is under 15, while almost a third of Japan's is 65 or older, according to a data insight from Our World in Data.

The figures are the UN's World Population Prospects 2024 projections for 2025. Worldwide, one person in four is younger than 15 and one in ten is 65 or older. In the Central African Republic, the country with the largest share of children, 49% of the population is under 15 and only 2% has reached 65. Japan, the country with the largest share of older people, is the reverse: 11% are children and 30% are 65 or older.

Share of the population under 15, 15 to 64 and 65 and over in 2025. Source: UN, World Population Prospects (2024), projections for 2025, via Our World in Data (CC BY)

A young country has to pay for schools, childcare and jobs for a fast-growing workforce, while an old one carries the cost of pensions and healthcare with fewer workers to fund them. "These differences in age distribution matter a lot for a country's infrastructure, socioeconomic conditions, and public spending," Hannah Ritchie of Our World in Data said.

Japan's internal affairs ministry put the share of people aged 65 or older at a record 29.6% in September, the highest among countries with more than 40mn people, and the National Institute of Population and Social Security Research expects it to reach 36.3% by 2045. The population is already shrinking: it fell to 123.3mn in 2025 from 124.5mn in 2023, according to IMF data. China and most of the EU have crossed a demographic tipping point beyond which a return to replacement-level fertility can no longer stop the decline.

The Central African Republic has a population of about 5.5mn. Its people live much shorter lives: life expectancy was 57.7 years in 2024, against 84.0 years in Japan, according to World Bank data.

Source: UN, World Population Prospects (2024), projections for 2025, via Our World in Data

This article was produced with the help of IntelliNews Lambda analytical tool