The table below shows the average annual rate of population growth for each of the 35 countries projected to grow most rapidly between now and 2050. Only four of the fastest-growing countries are located outside of Africa (Iraq, the Palestinian Territories, Mayotte, and French Guiana).
Populations grow when birth rates are higher than death rates and/or when immigration rates are higher than emigration rates.
The 35 countries that are projected to grow the fastest over the next 35 years:
|Democratic Republic of the Congo||2.65|
The two factors that affect future population size are the current (or base) population, and the population growth rate. In the example below, you can see that in 1950 Niger and Lithuania had the same population (Lithuania’s was actually 7,000 higher, which you can’t see in graph because the scale is in millions). Niger pulled ahead the very next year, in 1951, and today the populations are estimated at 19.9 million in Niger and 1.9 million in Lithuania. By 2050 they’re projected to have 72.2 million and 2.4 million people, respectively. By 2100, 209.3 million and 2.0 million.
In other words, over the course of a century, two countries that started with the same population size will diverge by a factor of over 100. It should therefore be no surprise that the fertility rate in Niger is currently 7.46 children per woman, whereas women in Lithuania have only 1.63 children on average.