The Nevada Education Department yesterday announced that the state’s high school graduation rate remains among the worst in the nation, and is last in terms of graduating African Americans. Education officials say Nevada’s overall rate for the 2013-14 school year was 70 percent. Nationally, the Education Department said 82.3 percent of students graduated — the highest rate since the department started using new, uniform measures in 2010. In Nevada, white students graduated at a 77 percent rate, Hispanics 65 percent and blacks 54 percent. Among students with limited proficiency in English, Nevada’s rate of 28.6 percent was better only than Arizona’s 18 percent.