I have no question about '占了', but I do think '在' is redundant in the sentence

haha thank you, that's funny example :D

Sorry, I made a mistake"他好胖，一个占了两人的地方". The correct sentence is "他好胖，一人占了两人的地方"

他好胖，一个占了两人的地方。 That is another example I can think of. That means He is so fat that he takes more space as two persons do. The original sentence"仅在中国和印度的人口就占了全球的三分之一" means the population in China and India is quite large. Just imagine there's 3 persons selected in random from the world I can draw the safe conclusion that the one in them must be chinese or indian.

can you give me more usage examples?