https://en.wikipedia.org/wiki/Educational_attainment_in_the_...
0.8% of Americans over 25 are earning minimum wage.
http://www.forbes.com/sites/jeffreydorfman/2014/01/30/almost...
That leaves 70% of American adults do not have college degrees and are earning above minimum wage. Of course, depending on how one defines things those numbers can go up and down, but it's not a stretch to say that most workers do not have college degrees and earn above minimum wage.
One last observation - starting your own business does not require a college degree. (Probably the most famous of those is Microsoft, and Microsoft has hired programmers without degrees.)
The author then has the gall to accuse others of using selective statistics to make their argument, and even throws out the 'class warfare' canard.
Similarly, that link only takes the federal wage into account - of course it's going to be abnormally low, given there are states with higher minimums. For example, Washington state has a minimum wage of $9.47/hour. A minimum wage worker in Washington won't show up in a study claiming $7.25 is the minimum wage.
Also, where do you mention 20%?