Niger currently has the highest birth rate in the world, with the average woman giving birth to 7.2 children. (nigerrenaissant.org)

The world’s population is aging, thanks to improving vaccines, antibiotics, and other medical technologies.

But some countries are still disproportionately young, with children comprising as much as 50 percent of their population.

According to the United Nations, disproportionately young populations typically belong to developing countries due to poverty, high child mortality rates, and a lack of infrastructure, medical resources, and education.

In recent years, scholars also cited European colonization of these countries during the 16th to 20th centuries as a cause to the overall lack of resources leading to disproportionately young populations.

The World Bank tracks the percentage of each country’s population under the age of 15, allowing us to see which countries had disproportionately young populations in 2018, the most recent year for which data is available.

The Republic of Niger is the youngest with 50.12% of its 23.4 million population composed of children 15 years old and under.

Niger is a landlocked western African country bounded on the northwest by Algeria, on the northeast by Libya, on the east by Chad, on the south by Nigeria and Benin, and on the west by Burkina Faso and Mali. The capital is Niamey. Two-thirds of its territory lies in dry tropical desert.

Also in the list but with the most children are Uganda (3rd), Nigeria (14th) and Afghanistan (19th). (Business Insider)

Here are the 25 nations where children make up the biggest percentage of the population: