You might consider looking at the study reported here https://www.theguardian.com/global-development-professionals...
> In 2012, ... developing countries received a total of $1.3tn, including all aid, investment, and income from abroad. But that same year some $3.3tn flowed out of them. In other words, developing countries sent $2tn more to the rest of the world than they received. If we look at all years since 1980, these net outflows add up to an eye-popping total of $16.3tn – that’s how much money has been drained out of the global south over the past few decades.
No comments on how good the study is, because I am not an economist.