Based on data from states for the 2010 graduating class, the National Center for Education Statistics estimated 78 percent of students nationwide earned diplomas within four years of starting high school, The Washington Post reported.
The last time the graduation rate was that level was 1974, the report said.
The report said the percentage of Hispanic students who graduate on time showed a 10-point jump during the past five years to 71.4 percent.
Mark Hugo Lopez, the Pew Hispanic Center's associate director, told the Post the findings confirm trends Pew has been tracking. The center said Hispanics are the nation's largest minority group.
"We've seen a surge in the Hispanic high school completion rate," he said.
Asian students had the highest graduation rate, with 93 percent of students finishing high school on time, followed by white students, 83 percent; American Indians and Alaska Natives, 69.1 percent; and African Americans, 66.1 percent.
In 2010, 38 states reported higher graduation rates and 12 states indicated flat rates, the report said. Nevada had the lowest graduation rate, with 57.8 percent, and Vermont had the highest rate, with 91.4 percent.
Lopez said the soft economy, among other factors, was one reason more students stayed in school, an observation echoed by Jack Buckley, commissioner of the National Center for Education Statistics.
"When the economy turns down or there are poor economic conditions, there's a lack of available jobs for high school dropouts, fewer jobs that they can actually be qualified for," Buckley said. "Historically, there has been a correlation between the dropout rate going down when the economy is weaker."