So, this is a fun one:
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A rapist often has more than one victim.
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Someone who disclosed to one person may well have disclosed to many.
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Rapists tend not to self-disclose.
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The definition of rape is badly established between both parties (it's an absolute minefield).
What you end up with is lots of small factors giving the illusion of a higher frequency by counting the same predator twice among women, and you also have factors that may cause predators not to be counted by men giving the illusion of a lower frequency.