Every parent or student opening a tuition bill has wondered why college costs so much.

Many parents can recall spending just a couple of thousand dollars a year to attend a state college in the early 1990s, a fraction of the average $12,000 a year in tuition and fees it cost this year to attend a four-year public college in New Jersey.

But while it's easy to just blame the colleges - indeed, much of the spending at today's colleges and universities does seem exorbitant - the total picture is more complex, according to a March report by the Center on Budget and Policy Priorities.

Public college budgeting is largely a balance of state aid and student tuition and fees. The percentage paid by each varies by state, but typically if state aid goes down, tuition goes up.

Over the last five years, the cost of tuition and fees at New Jersey public colleges has increased 13 percent, or about $1,429 per student according to the report. The amount of state aid the colleges received during the same period dropped 27 percent, or about $2,549 per student.

The report shows that pattern being repeated in states all over the country since the recession. States on average have cut state aid by 28 percent, or about $2,350 per student. Tuition nationally has increased 27 percent, or $1,850 per student.

The report notes that the recession just accelerated a long-term shift of the cost of college from the states and onto students and their families. Over the last 25 years, the average increase in tuition has just made up for the loss in state aid.

About two-thirds of all college students now graduate with debt averaging about $26,600 nationally and no guarantee of a job. Even families that tried to plan and save for college have been unable to keep up with the cost increases, according to the Institute for College Access and Success.

Nationally there is a call to rethink how to fund higher education and make sure students graduate as quickly and as cost-effectively as possible, without also cheapening the quality of the education they get.

Among the proposals have been more use of community colleges and more online courses as lower-cost options. These may not have the panache of living on a college campus for four years, but they can help prevent some of the sticker shock of the post-graduation loan payments.

The report calls for states to renew their investment in higher education. State legislators love to complain about the cost of college, but rarely acknowledge their own role in the increased costs to students.

New Jersey voters did approve a $650 million bond in November to help pay for the cost of more classrooms - a cost colleges had just been passing on to students. But a massive infusion of direct state aid is unlikely. Gov. Chris Christie is proposing an aid increase in next year's budget, but it will only cover the increase in state-paid employee benefits.

Ultimately it's up to students and their families to think realistically about their goals when applying to college.