It’s not uncommon to hear that the growth in student loan debt is like a time bomb threatening to blow up the U.S. economy. Now, you can watch it tick.

The outstanding balance of the nation’s student loans is growing by an estimated $2,726.27 every second according to the clock above developed for MarketWatch by StartClass, an education data site. As policymakers and pundits debate ways to tackle Americans’ $1.2 trillion in student loan debt, this student-loan debt clock provides a window into the growing risks to the economy as well as to student loan borrowers and their families.

The good news is that the debt is growing at a slightly slower rate than when StartClass first made the calculation for us several months ago. When the clock only included data up until the first quarter of 2015, student debt was rising by $3,055 every second. Now with second quarter 2015 data factored in, the debt is growing by about $328 less per second.

Still, Skyrocketing college costs, cuts to public funding for higher education, stagnant incomes and the growth in the college-going population are largely to blame for the uptick in outstanding student loans over the past decade. Now, about 40 million Americans are carrying some student loans and about 70% of students graduate college with debt.

This burden is likely preventing many of these Americans from buying houses and cars and fueling economic growth in other ways, according to research from the New York Federal Reserve and others. And only 37% of borrowers are actually paying down this debt.

“We have gained an increasing understanding that how we finance post-secondary education has significant effects on a variety of critical economic outcomes, including economic growth and inequality,” William C. Dudley, the president and CEO of the Federal Reserve Bank of New York said at a student loan data conference earlier this year, according to prepared remarks.

Modeled on the famous National Debt Clock, the student loan clock offers an alarming portrait of the problem in aggregate, but certain types of borrowers are suffering more under the weight of student loan debt than others. For many, taking out student loans is a worthwhile investment that helps to increase their earning potential. But borrowers who never reap the benefits of the education they went into debt to obtain are more likely to struggle to pay off their loans. Sixteen percent of borrowers who never finished their program are behind on their payments, according to data released last month. By contrast, just 4% of bachelor’s degree recipients and 3% of borrowers with graduate degrees report being behind on their payments.

“Many of the people with the biggest problems don’t have a lot of debt,” said Sandy Baum, a senior fellow at the Urban Institute. Lower levels of debt can often signal that a borrower attended fewer years of school and therefore never graduated. “The concern should not just be with the dollars of debt, but with who’s borrowing, whether they’re getting an education that serves them well and what it will mean for them in the future.”

Methodology

Researchers at StartClass used Federal Reserve data from 2006 to 2015 to estimate the per-second growth rate in student loan balances. They subtracted the amount of outstanding student debt in the first quarter of 2006 from the amount of outstanding student loan debt in the first quarter of 2015 and divided that number by the number of seconds in a quarter and then divided that by the number of quarters between the first quarter of 2006 and first quarter of 2015. The clock is meant to be used as an estimate.