Students in Kentucky take a practice test in 2011. (AP/The Enquirer/Patrick Reddy)

This year’s high school graduates were less likely to demonstrate college readiness on the ACT admission test than those who took the exam the year before, according to results of the college admission test released Wednesday morning. ACT officials attributed the falling achievement levels to a rise in the number of students who took the exams.

Nearly 2.1 million graduating seniors took the ACT, the nation’s most widely used admission test, an all-time high. They amounted to about 64 percent of the nation’s Class of 2016. An estimated 59 percent took the test in the previous class.

ACT is expanding in part through a growing number of contracts to test all high school juniors in various The College Board — owner of the rival SAT test, which released a revised version this year — also has a series of state contracts. Many students take both the ACT and the SAT.

ACT reported that 38 percent of the students from the Class of 2016 who took the test met its “college readiness” benchmarks in at least three out of the four subjects the test covers — English, math, reading and science. In 2015, 40 percent reached that threshold. More than a third of the students — 34 percent — failed to meet the benchmarks in any of the four subjects, an increase from 31 percent the year before.

The ACT is scored on a scale of 1 to 36. In standardized testing, it is often the case that scores go down when participation rises.

“This year’s ACT-tested class is more representative of the student population than any we’ve ever had,” ACT Chief Executive Officer Marten Roorda said in a statement. “We have likely added many more underrepresented students who may not have been preparing to go to college. In a situation such as this, it’s not at all surprising that overall achievement levels went down.”

Statistics released Wednesday show a slight decline in average scores nationally:

  • The national average composite score was 20.8, out of a maximum 36. That was down from 21 in 2015.
  • The average score in Virginia, where 31 percent of graduates took the test, was 23.3. That was down from 23.1 in 2015.
  • The average score in Maryland, where 27 percent of graduates took the test, was 23. That was up from 22.7 in 2015.
  • The average score in the District of Columbia, where 44 percent of graduates took the test, was 22.2. That was up from 21.1 in 2015.
  • Massachusetts had the highest average score for any state this year: 24.8. Its participation rate was 28 percent. Its 2015 score was 24.4.
  • The lowest average score was 17.7 in Nevada, where the participation rate was described as 100 percent. Its 2015 score was 21.0. (But its participation rate in that year was far lower, 40 percent.)

The ACT this year drew criticism for its handling of a revision to its optional essay, which was scored for the first time on a 36-point scale. Many students and parents said the new scoring procedure for the essay appeared to produce results that were sharply lower than what they expected. Some filed appeals and obtained upward score revisions.

In June, ACT announced that the essay scoring would change again, to a scale with a minimum score of 2 and maximum of 12, starting with the September national test. The change in essay scoring will not affect the overall composite score because the writing section is optional and separate. But it might alleviate the concerns of some students who had worried about how a middling essay score would be perceived compared to a high composite.