Academic Study shows that 90% of porn shows violence against women: details here
Researchers carried out a blow-by-blow analyses (literally) of the 50 top selling porn videos in the USA. This isn't niche porn, this is mainstream pornography. They found that nearly 88% of scenes showed aggression being carried out against women, including hitting, choking, gagging. This actually represents a significant under-estimate of the level of violence, since one woman being hit numerous times by several men in one scene was only scored as one act of violence. Further, the level of violence now seen in mainstream porn will have increased significantly since 2010, when this study was carried out.