29%:The share of college undergraduates who are traditional students.

The word “college” tends to call to mind images of fresh-faced young students studying, living and, yes, partying on or near leafy suburban campuses. But that picture only describes a small fraction of the nation’s 18 million undergraduates—even though such students dominate the public debate over the value of a college education.

First of all, more than 40% of all undergraduates in the 2011-2012 school year were enrolled in community colleges and other two-year institutions, according to Education Department data. Of the ones in four-year programs, more than one in five attend school part-time. That leaves a bit more than 8 million students who are enrolled full-time in four-year schools, or 45% of all undergraduates.

That figure hasn’t changed much in recent years. But what has changed is where they’re going to school. In 2001, less than 4% of full-time, four-year students attended for-profit schools. A decade later, that figure was nearly 11%, and has almost certainly continued to rise. That leaves 7.3 million full-time students in four-year programs at public or nonprofit colleges.