New York's graduation rate increased slightly to 78.1 percent last year but remained below the national rate of 82 percent. The State Education Department says Monday the four-year graduation rate for students who began high school in 2011 was 1.7 percentage points higher than for the previous class. But the department says it's still concerned by the nearly 7 percent of students, around 15,000 of them, who dropped out of high school.