The vast majority will happen to women who know the rapist.
Which is why rape is so damn hard to prove in the majority of cases, it comes down to he said/she said with no witnesses and the crux of the case is either consent from the outset, ability to consent or whether consent was revoked.
Stranger rape can often be easier to prove because of the lack of 'relationship' and often more obvious forensic evidence to support a prosecution.
Unfair, however you look at it.