Borrowers with student loan balances over $50,000 have increased almost 10 percent in the past decade, according to a data analysis from the Brookings Institute.

Historically, it was mostly graduate students, PHD candidates or those in the medical field graduating with large amounts of debt. This didn’t concern many economists because, as Brookings Institute senior fellow Adam Looney said, those people went on to high-paying jobs and were able to pay off their debt in a reasonable timeframe.

However, the rising cost of an undergraduate education and expanded borrowing limits has lead to a significant increase in non-repayment rates. Additionally, the expansion in student lending - and its associated risks — grew across all groups: undergraduates, graduates and for parents enrolled in higher education.

“I’m concerned about some of the students taking out these loans are not taking out the loans to pursue high quality or really valuable educational investments,” Looney said. “Students who borrow to enroll in a program that they don't finish or where the program doesn’t lead to a high-paying job, they're gonna struggle. And they do seem to be struggling.”

The analysis concludes that the rise in attendance at for-profit institutions is also to blame. In 2014, 20 percent of borrowers with balances above $50,000 had taken out student loans to attend for-profit colleges. In 2000, that number was less than 5 percent.

Multiple studies have shown enrollees in for-profit institutions have high drop-out rates, lower loan repayment rates and usually have a harder time finding a job after graduation.

Looney’s report also noted that there is a lot more lines of credit open to students in the past 12 years. Since 2006, the amount one person can borrow over their entire academic career has increased. Additionally, new loan products have offered lines of credit to more people.

“Like the parent PLUS loan or the graduate PLUS loans where there are no limits and there's kind of many more opportunities to borrow at programs that are exclusively online programs,” Looney said. The paper calls on policy-makers to reduce loan limits, eliminate certain high-cost loans and reduce the risk for taxpayers.