AUGUSTA, Maine — The high school graduation rate increased for the fourth straight year in Maine, the state Department of Education announced on Thursday.

In 2013, 86.4 percent of the students in Maine who began ninth grade in the fall of 2009 graduated on time, the statement said.

Education commissioner Jim Rier congratulated schools, but the DOE’s prepared statement said that there is a “wide graduation-proficiency gap” and a high rate of students have to take remedial courses once they get to college, suggesting that many students are not graduating college-ready.

“While I am encouraged to see a continually climbing graduation rate, it’s more important to me that our college and career readiness rates are also rising,” Rier said in the statement.

In the fall semester of the current academic year, 11.4 percent of students from Maine high schools who enrolled as freshmen at one of the University of Maine System’s campuses and 52 percent who enrolled in one of Maine’s community colleges were required to take a remedial math or English course, according to reports released by UMS and theMaine Community College System in January.

Maine students in the state’s public higher education institutions appear to be doing better than national averages.

About 20 percent of students entering a four-year college take remediation courses, according to a 2012 study from Complete College America, a nonprofit based in Washington, D.C.

Fifty-eight percent of recent high school graduates who enrolled in community colleges across the country had to take at least one remedial course, according to the Community College Research Center at Columbia University’s Teacher’s College, citing a 2006 study.

Rier said the state’s move to a new system of awarding diplomas will help ensure that students graduate prepared for life after high school.

“As Maine moves toward awarding diplomas based on proficiency rather than time served, students can be more confident the diplomas they’ve earned signify they are adequately prepared for success at the next step,” he said.

Under the proficiency-based diploma system, students will have to demonstrate they have mastered the state’s education standards in order to receive a diploma. There will be less emphasis placed on how many classes students have taken during their high school careers.

Students who are in eighth grade now and are entering high school in the fall will be the first cohort to graduate under this new system.

Maine’s graduation rate puts it in the top 15 states in the nation, the DOE statement said.