One year after a big gain, Louisiana's public high school graduation rate slipped for the Class of 2016, state officials announced Friday.

The figure is 77 percent, down from 77.5 percent for the Class of 2015, which featured the second largest increase in the previous 10 years.

State Superintendent of Education John White downplayed the drop, and he said steady gains are a challenge since some public high schools have graduation rates in the 50's and 60's.

Last year the rate rose from 74.6 percent to 77.5 percent.

"It is not an easy thing to go up three points across the state and keep that gain," he said. "The statewide graduation rate is the function of 400 schools."

White said he is most concerned about the 23 percent of students from the class who failed to earn diplomas.

Louisiana's high school graduation figure has long been low nationally.

The U.S. average was 83 percent for the Class of 2015, more than five percentage points higher than Louisiana.

In the Baton Rouge area, the latest results include Ascension, 87.9 percent; East Baton Rouge, 67.8 percent; Livingston, 83.2 percent; West Baton Rouge, 77.7 percent; Zachary, 89 percent; Central, 86 percent and Baker, 60.5 percent.

In the New Orleans area: Jefferson, 75.7 percent; St. Charles, 87.4 percent; St. John the Baptist, 74.1 percent; St. Tammany, 82.8 percent; St. Bernard, 86 percent and Orleans, 72.1 percent.

State officials have targeted an 80 percent rate for years.

A 2009 state law mandated students reach that figure by 2014. However, the graduation rate then was 74.6 percent, and the law carried no consequences.

The state's goal by 2025 is a 90 percent graduation rate.

"The Class of 2016 maintained the graduation gains of preceding classes, and exceeded them in the education levels they achieved," White said in a statement.

"More students than ever before are graduating already having earned college credit and high-value workplace credentials," he said.

"Our policies are working. But there is much left to be done. Even today, too many students do not graduate on time, and too many graduates are not clearly qualified for the next phase of education," he said.

On the latest snapshot White told reporters,  "No one should ever be happy with a 77 percent graduation rate, or be satisfied with it."

The good news, he said, is the state has an effective plan in place for improvements.

Last year the news was better.

The rate then rose from 74.6 percent to 77.5 percent, which state leaders hailed as a sign the state's longtime push to improve how students performed in the classroom was working.

Public school achievement here has lagged behind much of the nation for generations, and only 29 percent of adults in Louisiana have a two- or four-year college degree.

Despite the slip the state has shown gains in the past five years, both in the rate and the numbers of students who collected high school diplomas.

The Class of 2012 had a 72.3 percent graduation rate, and 35,332 students met diploma requirements. The Class of 2016 included 38,842 finishers.

The ranks of black students who graduated has grown 1,639 since the Class of 2012 while economically disadvantaged students who graduated rose by 5,297.

Those rates for the Class of 2016 are 71.4 percent and 71.2 percent respectively.

The graduation rate for students with disabilities is 45.1 percent.

The rate of students who applied for college financial aid – known as FAFSA – is 61 percent, up from 48 percent two years ago. FAFSA stands for Free Application for Federal Student Assistance.

Starting with the Class of 2018, students will have to apply for the assistance or fill out a form declining to do so.

White and others have said students here, especially those from low-income families, are leaving millions of dollars of aid on the table by not pursuing the assistance.

Follow Will Sentell on Twitter, @WillSentell.