Where can I find statistics for how many medical students take the Hippocratic Oath?

They all do. It's not legally bounding or anything, it's just supposed to be the way we're supposed to learn, practice, and teach.

It's the first thing you do when you get into medical school.

For me, it was about the last thing I did, at about the time of graduation. I understand some schools use a modernized version of the Oath, but believe all physicians take it.