With student loans reaching an all-time high, it's no surprise that many are now questioning whether their education is worth the expense. The average 2015 college graduate completed their education with 35,051 in student loan debt, according to a study by Edvisor, and a survey by Salary.com While not all degrees are created equal, and you can always find a career in a field you didn't major in, certain degrees are a better bet for students looking for the highest return on their education investment. In fact, a 2015 report by Georgetown University's Center on Education and the Workforce estimated that the difference in lifetime wages between the highest- and lowest-paying college majors is about 3.4 million. While some of the highest-paying tech employers have expressed an interest in hiring non-STEM graduates, science, technology, engineering, and math degrees still dominate the top 10 and much of the remaining top 50. But earning a STEM degree, which accounts for 20% of all college degrees, doesn't necessarily guarantee a high salary.