I suspect real statistics are difficult to come by. They might be kept state by state, but it’s probably apples and oranges, as states probably have different standards on what is abuse, etc. I’m not trying to be slippery, but I bet that is the case.
Thanks for looking! I am going to follow up on this roundup of existing literature on the subject, see where it goes:
http://www2.ed.gov/rschstat/research/pubs/misconductreview/index.html
But not tonight, I got things to do :0)