The relationship between Imperialism/neo-colonialism and current poverty? Facts and stats?

I am doing an essay on why wealthy nations should share wealth and send aid to developing countries and one of the reasons is because many wealthy nations exploited now poor states, which is one reason they got so rich. But does anyone have any facts or statistics like say.... of all the countries that were colonized by Europe in the Imperialism age "X number" are now in extreme poverty... but like a real one with sources and everything..help is greatly appreciated