The total number of people in Africa increased from 229 million in 1950 to 630 million in 1990 .
In some African states , more than half the population is under 25 years of age .
The total number of people in African increased from 229 million in 1950 to 630 million in 1990 .
In some African states , more than half the population is under 25 years of age .