They make up very large percentages of the population in SD and AK, not sure about OK and are disproportionally committing/being accused of sexual assault- a quick google shows this. These typically aren't juicy stories to the media as reporting privileged white males, athletes of any race sexually assaulting women or any vile gang rape broadcast live on Facebook. So I'll agree with you that cases of Native American sexual assault don't get as much of a rise out of most people (though this probably wasn't the point you were trying to make). I seem to recall much discussion here about the Stanford swimmer rape case and denouncement from folks on both sides of the aisle, and of course the Rolling Stone case (which obviously would since it had a direct tie to the University).