Compare the world population index for 1960 to the world population index for 2000. Then express the world population in 2000 as a percentage of world population in 1960. Compare the world population index for 1960 to the world population index for 2000. Then express the world population in 2000 as a percentage of world population in 1960. a. 100% b. 400% c. 200% d. 50%