Society as a whole isn't more tolerant today than in the 60s. That which is tolerated or "in" today was "out" in the 60s but the overall tolerance level doesn't seem to have changed. We have new groups which get persecuted today but the persecution hasn't exactly stopped. We have new groups which are more tolerated today such as homosexuals but this doesn't mean other new groups haven't replaced homosexuals in being persecuted.
So the data would have to show that humans in general are becoming more tolerant overall and it's not good enough to just look at any particular group which might go in and out of fashion.