From the Center for Disease Control in 2010:

• The majority of women who reported experiencing sexual violence, regardless of their sexual orientation, reported that they were victimized by male perpetrators. The most stark numbers were for rape, where 98.3 percent of bisexual women and 99.1 percent of lesbians reported their perpetrator was a man.

More:

The Encyclopedia of Victimology and Crime Prevention states, "For several methodological reasons – nonrandom sampling procedures and self-selection factors, among others – it is not possible to assess the extent of same-sex domestic violence. Studies on abuse between gay male or lesbian partners usually rely on small convenience samples such as lesbian or gay male members of an association."