CARSON CITY, Nev. (AP) — Nevada's statewide graduation rate has ticked up thanks to improvements at the massive Clark County School District.

State education officials said Thursday that the preliminary graduation rate for the Class of 2015 was 70.9 percent, up from 70 percent the year earlier.

Clark County logged a 72 percent graduation rate, up from 70.9 percent the year before. The district is by far Nevada's largest.

Washoe County had a 75 percent graduation rate, up from 72.7 percent a year earlier.

State Superintendent Steve Canavero said he was encouraged that more students were finishing high school, but was troubled by a bullying trend highlighted in the Thursday report.

State officials said there were nearly 5,200 reported bullying incidents that led to discipline last school year, up significantly from 3,800 the year before.