2.	Assuming a moderate decline in current fertility levels to the UN's medium variant of 2.8 children per woman by 2050, Africa's current population is expected to double to 2.1 billion by mid-century. At this level, the continent would account for nearly a quarter of the world's population.

3.

By the close of the 21st century, even assuming the average fertility rate for the continent has by then fallen to the replacement level of 2.1 children per woman, Africa is projected to have a population close to 3.6 billion people, representing 35% of the estimated world population of 10.1 billion.

4.	If Africa's fertility rates were to remain unchanged over the coming decades, the population of the continent would grow extremely rapidly, reaching three billion by 2050 — and an incredible 15 billion by 2100, or about 15 times Africa's current population.

5.	Even if fertility rates were to fall instantly to replacement levels, the African population would continue to increase due to its young age-structure (half the population is less than 20 years old), growing to 1.5 billion in 2050 and 1.8 billion in 2100.

6.	With high rates of natural increase, in excess of 2%, by the close of the century the population of Africa's 33 least developed countries is expected to reach 2.2 billion, or slightly more than a fifth of the world's population at that time.

7.	Nigeria — already Africa's most populous country at 158 million — is expected to grow to 730 million by century's end, making it a good deal larger than Europe's projected population of 675 million.

8.

While Nigeria is currently the only African country with a population exceeding 100 million, ten other countries are expected to join that club before the close of the century: the Democratic Republic of Congo, Egypt, Ethiopia, Kenya, Malawi, Niger, Sudan, Tanzania, Uganda and Zambia. Together, the population of these 11 African nations is expected to reach 2.4 billion by 2100, representing about a quarter of the world's population at that time.

9.

In comparison, none of China's 23 provinces yet has a population exceeding 100 million. Guangdong, Shandong and Henan come very close to the 100 million benchmark, having populations, respectively, of 98 million, 94 million and 93 million people (as of 2010). Similarly, none of the European Union's 27 member states has over 100 million people. The closest are Germany (with a population of 82 million), France (63 million) and the UK (62 million people).