The answer is 200%.
If we see the world population index and compare the population in 1960 and 2000, we see that population in 2000 is double than 1960.
World population in 1960 = 3,007,751
World population in 2000 = 6,104,538 which is approximately double than 1960.
So when we express it as percentage multiply 2 with 100 and we get the percentage 200.
