I originally found an article talking about this information, however the graphic inside the article was just atrocious and really bothered me (probably more than it should have). So, again, I made one of my own. Copying the numbers from the article into a manageable form was the hardest part.
I really wish this data could have continued past 1972 - even if it had to zoom in on the non-clean shaven portion - but alas the original article stopped at 1972. I've even since tried searching for comparable data to fill in the blank space between then and now and still have found nothing. Scientists, get on it!