I wonder if those who quote statistics of the proportion of male rapists compared to female rapists are aware that not all jurisdictions define rape in a way that is even possible for women to be defined as rapists. This can obviously drastically affect the outlook of comparative rape statistics. In my own country, for example, a woman can only be convicted of ‘sexual assault’ (which carries lower penalty tariffs) unless she is directly involved in the rape of a woman by a man.
This is not the case in Brazil. Brazil’s definition of rape is gender-neutral (which is not to say the application of the law in Brazil is: I have no knowledge on that). Brazil’s definition of rape is very much wider than most jurisdictions, covering what most would describe as ‘sexual assault,’ and this could explain why the rape statistics for that country is relatively high.
The maximum penalty for rape/sexual assault in Brazil seems fairly low in comparison to other jurisdictions.
Most male victims of a female rapist would never come forward about it. Men are expected to be strong and their sexuality open to any woman who wants them. This is an explanation of why a high proportion of victims who charge a female rapist, where such charges are possible, are homosexual.