The nation’s illiteracy rate has dropped significantly from 40 years ago.

According to a survey on 12-thousand adults by the National Institute of the Korean Language, an estimated 620-thousand out of 37 million South Korean adults cannot read or write. That’s one-point-seven percent of South Korean people, down from seven percent in 1970.

The study also showed big differences according to gender and age. The illiteracy rate for women was two-point-seven percent, much higher than that of men's, which stood at one-half percent.

According to the survey, almost all Koreans in their 20s to 40s are able to read and write, but some 20 percent of elderly people in their 70s, are not able to.

The "semi-illiterate," those who can read but cannot understand the meaning of a sentence or a story, account for five-point-three percent, or some one-point-nine million people.