The four-year graduation rate in Gwinnett County Public Schools increased 2.3% last year to about 83.2%, according to data released last week by the Georgia Department of Education.

The rates increased in 17 out of 24 high schools in the county, with Discovery, Lanier and Mountain View high schools and the Gwinnett Online Campus posting the largest gains.

“We have a strong staff of teachers and counselors who are incredibly focused on ensuring that our students are successful and graduate on time and we look to continue to improve on this past year’s success,” Mountain View High School Principal Keith Chaney said in a news release.

This year, the Gwinnett School of Mathematics, Science, and Technology, McClure Health Science High School and Lanier and North Gwinnett High Schools had the highest graduation rates.

The average graduation rate statewide is 83.8%. Gwinnett County’s graduation requirements are stricter than those of the state.

As required by federal law, the graduation rate is the number of students who graduate with a regular diploma in four years divided by the number of students in the senior class.

The school district’s five-year graduation rate for the Class of 2019, including students who graduated after summer school, is 84.45%.