Chart 3.1. Composition of Population in Low- and High-income Economies, 2000

In many low-income countries, the large difference between the percentage of people of childbearing age and more elderly adults causes population momentum which keeps population growth rates high even when fertility rates drop. In many high-income countries, where fertility rates are below replacement level and the largest segments of the population are older, populations will increase much less. To see the projected composition of population for low- and high-income economies in 2030, look at Chart 3.2.