]green]. But wouldn't masturbation have had a category all of its own?

It certainly did, Shona - In Victorian Public Schools (and right up until WW2 in some of them, I believe) it was known as "Self-Pollution."

Sorry to be a bit late with this - I've only just got back to work today after a long and arduous week-end, in which pollution of any sort didn't figure at all.