How do you find out the percentage between 1500 1800?

How do you find out the percentage between 1500 1800?
First of all, you should decide where you want to focus on. Do you mean America, or other countries? Also, you might want to focus on what exact topic that you want to discuss. Do you want to know how many slaves were shipped and to where? Or do you want general statistics about slavery worldwide?

For American statistics, I would suggest to look in JSTOR, or do a Google search and look for a scholarly website.