India and Nigeria will constitute 52% of all Commonwealth countries’ total population by 2100.

Source: World Population Prospects 2017, UN Population Division

The population of Commonwealth countries collectively was 2.4 billion in 2015. According to UN projections, the combined population of Commonwealth countries is expected to grow at a faster rate (6.6%), on average every five years, than the rest of the world (4.4%) till 2100. The population of India and Nigeria are expected to grow by 16% and 340% respectively by 2100.