COLUMBIA — Test scores for graduating seniors taking the ACT college entrance exam remained stable in South Carolina compared to a year ago, even as a record number of students took the test, data released Wednesday showed.

The class of 2014’s average composite score was 20.4 on a 36-point scale, unchanged from last year. The national average increased by one-tenth of a point, to 21.

The data includes scores posted by public, private and home-schooled students. More than 2,000 additional seniors took the test compared to 2013.

The exam is supposed to measure how well students understand academic material they must have to succeed in college.

“While South Carolina’s average ACT composite score was slightly under the national average, its proximity proves that we are making progress. These are positive results that we can build on for the future,” State Superintendent of Education Mick Zais said in a statement.

Zais pointed to the increase in scores for public school students as evidence of progress. Those increased by one-tenth of a point to 20.2.

Twenty-three percent of South Carolina’s test-takers met so-called “benchmarks” in all four subjects: English, reading, math and science. That’s up from 22 percent in the state last year. Nationally, 26 percent of students met all four benchmarks.

Students who meet the benchmarks are more likely to be successful in college and go on to earn a degree.

Both the ACT and SAT are accepted by most colleges. The SAT has historically been more popular in South Carolina, but ACT participation has grown over the years.

The report said 58 percent of the state’s graduates took the exam, or 23,232 students. In 2013, 20,868 students in the state took the test.

Zais said 12.7 percent additional public school students took the test compared to 2013. There was an 11.3 percent increase in the number of overall students who took the test this year compared to 2013, he said.