Yes, E is the correct answer, but why choose it over D?
doesn't Despite also show a contrast?
The correct answer not only needs to make the correct comparisons, but it also needs to modify the subjects correctly.
The first sentence needs to modify US Citizens. D's usage distorts the original meaning of the sentence.
"Despite having only 5% of the world's population, United States citizens...." suggests that its the citizens that are having the world's population...which doesn't make sense.