The column graph compares the changes in the proportion of population in India, China, the USA and Japan in 1950 and 2000, and also indicates the projections for 2050. It is clear from the graph that China had the highest percentage of world population in 1950 and 2000, but estimates show that India will take the lead by 2050.
In 1950, China accounted for a little over a quarter of the world’s population. Although it decreased to a little under a quarter, it was still the highest in 2000, compared to the other three countries. It is estimated that the population of China will continue to drop and would reach approximately19% by 2050.
India showed an opposing trend to China. The population in India in 1950 was 15%, which was considerably lower than that of China. However, the population increased moderately to 19% by 2000 and is further expected to grow and reach nearly 20%, which would be the highest among the given countries by 2050.
When it comes to the population of the USA and Japan, both showed a decrease from 1950 to 2000. It is predicted that the percentage will remain the same in the USA, whereas in Japan, the population is likely to keep falling till 2050.
Overall, Japan had the least population in the given period, and the population is expected to decrease to approximately 3% by 2050. 
The column graph compares the  
changes
 in the proportion of  
population
 in India, China, the USA and  
Japan
 in 1950 and 2000, and  
also
 indicates the projections for 2050. It is  
clear
 from the graph that China had the highest percentage of world  
population
 in 1950 and 2000,  
but
 estimates  
show
 that India will take the lead by 2050.
In 1950, China accounted for a  
little
 over a quarter of the world’s  
population
. Although it decreased to a  
little
 under a quarter, it was  
still
 the highest in 2000, compared to the other three countries. It  
is estimated
 that the  
population
 of China will continue to drop and would reach approximately19% by 2050.
India  
showed
 an opposing trend to China. The  
population
 in India in 1950 was 15%, which was  
considerably
 lower than that of China.  
However
, the  
population
 increased  
moderately
 to 19% by 2000 and is  
further
  expected
 to grow and reach  
nearly
 20%, which would be the highest among the  
given
 countries by 2050.
When it  
comes
 to the  
population
 of the USA and  
Japan
, both  
showed
 a decrease from 1950 to 2000. It  
is predicted
 that the percentage will remain the same in the USA, whereas in  
Japan
, the  
population
 is likely to  
keep
 falling till 2050. 
Overall
,  
Japan
 had the least  
population
 in the  
given
 period, and the  
population
 is  
expected
 to decrease to approximately 3% by 2050.