A weakened economy continues to drive the cost of public universities up, with California as the catalyst, a new report found.

The national average for public four-year institutions increased 8.3 percent in the 2010-2011 and 2011-2012 school years, October report noted. But excluding California, the national increase was 7 percent.

There are about 22.5 million students enrolled in post-secondary school in the United States, 2.1 million of them being in public California schools.

“The past couple of years, California has had very large and unpredictable raises,” said Karen Humphrey, executive director of the California Postsecondary Education Commission. “It’s a serious concern because students are taking longer to graduate, or not even graduating at all.”

California enrolls about 10 percent of the nation’s full-time four-year public college students, which have faced a 21 percent hike in fees since last year, according to the report.

California’s increase is 4 percent higher compared to Arizona, and 18.5 percent higher than South Carolina and Connecticut.

“There’s a question about how much California is committed to affordable and acceptable higher public education,” Humphrey said. “Raising fees constantly at great rates is not making college successful, it’s just shifting the burden to private individuals and families.”

The national average for one year of in-state tuition at a four-year public university is $8,244, about $1,200 less than California’s cost, according to the report. For out-of-state costs, the national average is $20,770, compared to California’s $26,863.

“The state budget is in far greater trouble than anyone has predicted,” Humphrey said. “The new budget passed in June chopped $1.5 billion from post-secondary schools, that’s the main reason for the excessive price hikes.”

Still, H.D. Palmer, deputy director for external affairs at the California Department of Finance, said colleges and universities are not the only areas of the state facing cuts.

“The cuts have been a result of California grappling with the worst recession since the Great Depression,” Palmer said. “Every aspect of the state has seen its share of cuts, it’s not just limited to education.”

According to the most recent study published in 2009, the national graduation rate of 63 percent has remained relatively unchanged since 1996, but a 2011 study found that only 52 percent of California students earn a bachelor’s degree in the same time period.

“Currently, no state is graduating as many students as they should,” Humphrey said. “There’s a definite link between the cost of school and graduation rates, and everyone in the country is having trouble graduating students and putting them in the work force.”