Hawaii high-schoolers posted modest gains in English, reading and science on the ACT exam, but many in this year’s graduating class appear unprepared for college-level coursework, according to results released Wednesday for the national college entrance exam.

The nonprofit testing company said in its annual report that fewer than a third of the students here who took the test, which was administered to them in 2015 when they were juniors, met the benchmark scores in three of the four subjects — reading, math and science — while less than 50 percent met the benchmark score for English.

A benchmark score is the minimum score needed to indicate a 50 percent chance of obtaining a B or higher in the corresponding college courses, which include English composition, algebra, social sciences and biology, according to the ACT.

Hawaii’s individual subject scores for 2015 edged up by less than 1 percentage point from 2014, while national averages fell slightly across subjects. Among the state’s public school students, the average composite score across the four subjects increased to 17.8 from 17.5; statewide it increased to 18.7 statewide from 18.5. The national average dipped to 20.8 from 21 out of a possible 36. In all, 94 percent of Hawaii’s 2016 graduating class took the exam last year.

The state Department of Education in 2014 began requiring all public school juniors to take the exam to help assess students’ college-and-career readiness. The ACT is mandatory in 20 states, and optional in others. Nationally, more than 2 million students last year took the ACT, representing approximately 64 percent of the nation’s graduating class.

Among the 20 states requiring all 11th-graders to take the ACT, Hawaii’s average composite score ranked No. 17, above South Carolina, Mississippi and Nevada. Scores were highest in states where the exam is optional and therefore only college-bound students are likely taking the test. Massachusetts, where 28 percent of high-school juniors took the ACT, posted the highest average composite score of 24.8.

In Hawaii, 12,232 students took the test last year as juniors — including 10,525 public school students. Forty-six percent of students met the college-ready benchmark in English, compared with 61 percent nationally. That’s up 1 percentage point from last year’s state results.

In reading, 30 percent of the isles’ students met the benchmark score, unchanged from last year, compared with 44 percent nationally. Meanwhile, 30 percent of students hit the math benchmark score, up 1 percentage point from last year, compared with 41 percent nationally. On the science portion of the exam, 23 percent of students hit the benchmark score, unchanged from last year, compared with 36 percent nationally.

Only 15 percent of Hawaii students met benchmarks in all four subjects, unchanged from last year, and significantly behind the national average of 26 percent. For public school students, the rate was 10 percent.

“Eighty percent of 2016 graduates who took the ACT test indicated their desire to earn a two- or four-year college degree, and we are encouraged by steady gains in our students’ college preparation and enrollment,” schools Superintendent Kathryn Matayoshi, said in a statement. “However, we recognize the need for more of our students to be ready for the rigors of work and study after high school.”

The department pointed out that in the years since the DOE made the test mandatory, public school students have made “steady” improvements in the individual tested subjects. Average scores in English, for example, have increased by 4 percentage points since 2014, and scores for reading, math and science have each gone up by 3 percentage points since 2014.

“Improvements in the recent ACT scores are a promising reflection of college readiness in Hawaii’s public high school graduates,” the department said in a news release.