North Dakota and almost every other state got a failing grade in college affordability in a new report on higher education. The report says North Dakota is a top-performing state in high school completion but has a big gap in the rate between white and American Indian students.

The study comes from the National Center for Public Policy and Higher Education, which evaluates how well higher education is serving the public. It gave F grades for affordability to 49 states. California got a C.

The affordability grade is based on how much of the average family's income it costs to go to college.

The report says that in North Dakota, poor and working-class families must devote 54 percent of their income, even after aid, to pay for public four-year colleges.

"For every dollar in Pell Grant aid to students, the state spends only 10 cents," the report says.

North Dakota got an A in completion, which measures students' progress toward their certificates or degrees. But the report said 17 percent of Native Americans graduate within six years compared with 48 percent of whites and called it "one of the largest gaps in the nation."

The report said North Dakota does well in providing college opportunities for residents and does fairly well in preparing young people for college. It said only a "fair proportion" of residents have a bachelor's degree and gave the state a D in that category, though it said the state has made improvements.

"If all racial/ethnic groups had the same educational attainment and earnings as whites, total annual personal income in the state would be about $300 million higher," the report said.