NEW YORK ( MainStreet) — Each year, the average amount of student debt seems more disconcerting than the one before, if only because it's bigger. What's more, these increases seem predictable as government support for students continues to decline relative to the incomes of borrowers and their families.

"The burden of paying for college has shifted from federal and state governments to families," says Mark Kantrowitz, senior vice president and publisher of Edvisor's Network, which provides information on student loans. "Family income is flat, forcing students to either shift their enrollment from higher cost colleges or graduate with more debt." Lower and moderate income students are priced out of the market.

In his new report, "Debt at Graduation" released last week, Kantrowitz focuses on the balances students have when they get their diplomas—the debt at graduation—rather than the number they thought they'd end up with when they first enrolled. That number is often much higher than expected.

By the same token, the amount of time needed to graduate has also increased. According to the Department of Education, it now takes an average of six years to get a BA when part-time students are factored in along with those that started at two-year schools.

Student debt at graduation estimates are based on one of two sources: the National Post Secondary Student Aid Study (NPSAS) or the Common Data set, produced by the Common Data Set initiative which provides data for publishers of college rankings such as Peterson's and U.S. News and World Report .

Federal PLUS Loans, which are co-signed by the borrowers' parents, aren't factored in to the Common Data Set studies, while NPSAS figures, which were used in the Debt at Graduation study, includes them.

The report found that the average debt for students getting a BA was $29,384 in 2011-2012. About one-sixth (15.5%) of undergraduates have federal PLUS loans, which raised the debt at graduation total for those borrowers to $35,432.

The report also found that less than 6.5% of undergraduates reach six-figure debt. Kantrowitz said it was not possible for an undergraduate to hit six digits without borrowing money from a private lender. Interest on Stafford loans are currently 3.85%. Many private loans are in or near double digits.

Grad and professional school loans are another story — those students can rack up six-figure debt without a private loan, although many borrow from those lenders as well, often when better alternatives such as PLUS loans are available.

"A significant number of graduate and professional students borrow from private loan programs," the report says, "despite the availability of the federal Grad PLUS loan program. About half of graduate and professional school students who graduate with six-figure student debt borrowed from private student loan programs."