I think the study should have not counted nurses who work in corrections and, maybe, psych, since verbal abuse is only to be expected in these kinds of environments. With that said:
It would be useful to know what percentage of these nurses: called the police and pressed charges for assault and battery, filed and pursued formal sexual/gender/whatever discrimination charges at their workplaces, etc.
In other words, what percentage of these people stuck up for themselves in a useful way. My guess--very few. I'm not "blaming the victim," here, but saying that when people do not experience severe consequences of their assaultive and abusive behavior, why would they stop doing it?