Education Minister Liz Sandals says 74 per cent of students get their diploma after four years, up 18 percentage points from when the Liberals took office nearly 10 years ago.
The graduation rate jumps to 83 per cent for students who take five years to complete the four-year high school program, an increase of 15 percentage points.
Sandals says it's very important to track the five-year graduation rate because the kids who don't quite make it in four years need extra help to make sure they succeed.
About 115,500 students needed the extra year to graduate, which Sandals says puts them in a better position to succeed.
Ontario was the last province to have a five-year high school curriculum, but it eliminated Grade 13 in 1984.
Sandals is the first Liberal cabinet minister to admit she was announcing a five-year graduation rate instead of just putting out the figure without stating the number of years it covered.