From which years/practice tests do the LSAT practice tests come from?

I would like to purchase a book of practice tests and I don't want my study material to overlap. I have read other responses to similar questions that say that some of the tests are unpublished, but I would like to know which published tests are used by Khan Academy. I don't necessarily need to know exactly which of the 10 available practice tests is which (although that would be nice) just which ones are used on this website.