BATON ROUGE, La. (AP) - Louisiana four-year high school graduation rate continues its upward trend, reaching 77.5 percent in 2015. The state education department says that's an all-time high and the fifth year the rate has improved.

The education department says black students remain below the average, but their improvement outpaced the state as a whole. The graduation rate for African-American students was 71.4 percent in 2015, up from 67.9 percent the year before and a growth of 12.5 percentage points since 2010.

Despite the improvements, Louisiana still lags the nation.

Louisiana's high school graduation rate grew 2.9 percentage points from the 74.6 percent rate in 2014. By comparison, the nation's graduation rate that year was 82 percent, according to the U.S. Department of Education, the latest year for which national data was available.