How can I find how much wealth was taken out of the colonies by Europeans?

So difficult, because the value of money has changed so much since those times. Also the things that money would buy are so different now - there weren't cars or computers or telephones or refrigerators in those days. There are estimates for the tonnage of gold and silver taken from South America, sorry, I don't have them to hand. Even that needs careful thought - Spain thought it would get rich from the gold and silver, but ended up as a poor nation after the gold and silver had passed through Spain.