But let's start with what is there: Total enrollment in degree-granting, public and private not-for-profit colleges and universities in the US from 1995 to 2012. What you see is mostly stability, if you assume the whole world of higher education is made up of these two sectors only: Some growth in each in the top chart (the population has grown, of course, over that time); a relatively stable distribution of private and public enrollments (where private colleges have always enrolled about 20% of the students); and percentage changes since 1995 that are virtually identical. (Hover over the line at any point to get the details).

Now, for the work: In the filter in the right, check the box labeled Private Not-for-profit, to add that population to the mix. The blue line appears, and you begin to see its effect on the other two sectors: By 2012, the for-profit sector enrolled over 11% of all students. Although the percent of total had fallen a bit by 2012, it still represented over 10% of all students enrolled.

What's more astonishing is the rate of growth: From 240,000 in 1995 to 1.8 million students in 2012, a 650% increase.

Before I publish the next chapter, what percentage of federal grant and loan aid do you think goes to these three types?