Terrible!
They probably do not report the incidences.
I know a guy who was almost raped in college. He was a basketball player and took medication to help him sleep. Well, he said two girls called his room (later discovered they were "big" girls), check to see if he sounded like he had taken his medicine by asking where his roommate was, went over to his dorm with rope and textbooks (I kid you not), and knocked on his door. When he answered the door they shoved the door open and hit him on the head the textbook. His suite mates heard the commotion but figured the guy was just having wild sex. They were struggling to tie him up when he said he cried out that someone was trying to kill him (because that's what he thought at first). The suit mates came in and helped and campus police were called. It was only after the girls were questioned that they found out the girls were trying to have sex with him. It was not reported to the local police nor did it go on record.
I was laughing as he told me about it, but stopped laughing when I saw the look on his face.
My initial reaction is probably one reason why cases of female raping males aren't reported.