Slave trade perspective:
http://blog.nationalgeographic.org/wp-content/uploads/2014/02/gitn_1027_Slave-Trade-2.png
Looks like it doesn’t include white folks captured by mooselimbs and put into slavery.
Never mind that, before the American Revolution you could actually buy white convicts to work on your farm or plantation. They had an iron collar around their neck to prevent them from escaping. With 7-year indentures, they were a lot cheaper than slaves, but many of them weren’t very good workers.
There are places where actual numbers can be researched, which further illustrates it.
This was primarily an old-world European problem.