The world population in 2009 was 6.18 billion people. Since India had 1.115 billion people in its borders, it means that India had about 18.04% of the total world population as its citizens.
We can get to the result very easily. All we need to do is to multiply the population of India by 100, and than divide the result with the number of the total world population.
1.115 b x 100 = 111.5
111.5 / 6.18 b = 18.04 %
