Ashley Greene will have to pay off at least $6,000 in student loans when she graduates from Valdosta State University. Without them I probably wouldnt be in college, she said. But the graduate of Union Grove High School, at 20, is not too worried about how she will pay off her student loans. She said she knows just about how much she can handle in student debt. Student borrowing has increased substantially from 1993 to 2004, though levels vary for graduates of different degree programs, according to a brief from the American Council on Education Center for Policy Analysis. The center focuses on issues such as financial aid.Greene, a full-time student at Valdosta, said that planning to pay for college is more than just a passing concern for her.I knew that I would have to work and take out a student loan, said Greene, who also receives Georgias HOPE Scholarship, which is available to high schools students who graduate with at least a B average.