Where are you getting your numbers? They sound to me like they come from the National Crime Victimization Survey. These are not reports to police, but the result of asking random people if they have been raped. I don't think that they sample prisoners, so they are probably highly biased against prison rape, but should catch some.
ETA: There is now a third thread, so send new comments there.
Since the first thread has exceeded 500 comments, it seems time for a new one, with Eliezer's just-posted Chapter 33 & 34 to kick things off.
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