Researchers say high school graduation rates have reached a positive milestone, though there's room for improvement.

Federal statistics from 2012 show that the graduation rate has reached 80 percent.

That still means one in five students don't get a diploma, but the researchers say the improvement can be expected to continue.

They project the high school graduation rate could reach 90 percent by 2020.

Growth in graduation rates among African-American and Hispanic students helped fuel the gains.