CONCORD, N.H. -- New Hampshire's fourth- and eighth-grade students continue to outperform their peers in most states on math and reading tests, according to the 2013 Nation's Report Card, which was released Thursday.

The report from the National Assessment of Educational Progress showed that students around the nation performed mostly better this year than they did when the tests were first given in the 1990s. The tests are given every two years to a sample of fourth- and eighth-graders.

In New Hampshire, 59 percent of fourth-graders and 47 percent of eighth-graders scored at or above the proficient level on the math test. That compares with 42 percent of fourth-graders and 35 percent of eighth-graders nationally.

At or above proficient means the students demonstrated solid academic performance.

In reading, 45 percent of the state's fourth-graders were at or above proficient, compared with 35 percent nationally. Among eighth-graders, 44 percent of New Hampshire students scored at or above the proficient level, compared with 36 percent nationally.

The results put New Hampshire in the top six states whose students were at or above proficient in all four categories.

Tim Eccleston, the state's NAEP program administrator, said several factors go into New Hampshire's relative success including small class sizes, per student spending and the percentage of parents with a college education. New Hampshire spent $12,183 per student, compared with a national average of $10,591 in 2011. In the same year, 58 percent of students in New Hampshire had at least one parent who graduated from college, compared with 47 percent nationally.

"We benefit from many things," Eccleston said. "You don't want to be satisfied where you are. You always want to say, ‘Is there room for growth?"'

The results come as a majority of states roll out use of the Common Core State Standards with the goal of better preparing the nation's students for college or a job.