It depends on the circumstances of the rape, for me as well - like most of you, I'd only even consider it if the 'cliched' rape elements were there. Certainly it didn't even occur to me to report at 16, because I'd voluntarily got into the man's bed (alone, at the time - I'd had a couple of drinks on an empty stomach and needed to lie down).
I've probably said this somewhere else, but a few months ago I mentioned that rape to an old friend, because she was telling me that he was back in town and wouldn't it be nice to catch up, and I said no it wouldn't, he raped me when I was 16. And she said "...it's funny, looking back to your teenage years, isn't it? It's easy to regret the sex you had then and remember it differently".
This is a friend of 16 years duration, who knows me well, and knows that I would have absolutely no possive motive for making that up - it was 16 years ago, why would I tell her that now if it was a 'regretted sex' issue? Surely i'd just not mention it at all? AND back then everyone knew he had form, wasn't to be trusted, tended to go for younger girls, etc. And still, and yet. Me, respectable married lawyer and mother, 16 years past the event mentioning it, and I can't possibly be telling the truth.
Thank god i didn't try and report at the time, then.