The chart below shows the percentage of the whole world population in 4 countries from 1950 to 2050.

The column graph compares the changes in the proportion of the population in India, China, the USA, and Japan in 1950 and 2000, and also indicates the projections for 2050.

Overall, in the 20th century China was the most populated country; however, in future India will lead China. Meanwhile the populace in all countries witnessed a decreasing trend except in India.

In detail, China had the highest percentage of the world population in 20th century. This figure fell from 26% in 1950 to 23% in 2000 and in 2050 it is expected to decrease further to 18%. India, on the other hand, had the second biggest population. Its percentage rose to 18% in 2000 from 15% in the beginning. This proportion is predicted to reach 21% in 2050 which would be the highest among the given countries by 2050.

In contrast, the population of the USA and Japan showed a decrease from 1950 to 2000. The USA noticed a drop of 2% in its populace reaching 8%. Similarly, Japan witnessed 1% fall in 2000 from 5% in 1950. It is predicted that the percentage will remain the same in the USA, whereas in Japan, the population is likely to decline till 2050 to 3%.