Janet Yellen, chair of the Federal Reserve, spoke at the University of Baltimore’s midyear commencement last week, and she was about as upbeat as any practitioner of the dismal science from whom the students will ever hear.

The economy is nearly at full employment, with prospects especially strong for college graduates, for whom the unemployment rate is an infinitesimal 2.3 percent. What’s more, grads can expect a “large” advantage in lifetime earnings over contemporaries with only a high school education.

Last year, college graduates’ earnings averaged 70 percent more than high school graduates’ pay; that is up from 20 percent in 1980, she said.

And the advantage kicks in quickly: Only a few years after graduation, it’s almost $18,000 a year, Yellen reported.

Student debt now totals $1.3 trillion, spread out over 44.2 million borrowers. Yet as Yellen pointed out, government data show that the vast majority of student borrowers who complete their degree programs find work that allows them to keep up with interest payments and eventually pay off the principal. According to studentloanhero.com, about 40 percent of student debt was incurred to finance graduate and professional degrees – that is, MBAs, MDs and law degrees, which enhance future earnings even more than a four-year bachelor’s.

Debt distress is disproportionately concentrated in certain segments of the market, including professional schools and for-profit four-year colleges. Solutions, if any, should be targeted and limited so as not to waste resources that could go toward other purposes, such as enhancing the prospects of those who do not attend college.