BEIJING -- Among Chinese families with primary and junior high school students, a third of all household educational spending was used for supplemental education in 2017, according to a survey by the China Youth Daily on Monday.

Supplemental education refers to educational products or services purchased from institutions or individuals other than schools for the purpose of developing a student's interest or improving the student's grades in school.

In urban households, supplemental education accounted for 42.2 percent of the households' total education spending in 2017, while the figure was 16.6 percent in rural households.

According to the survey, 47.2 percent of all primary and junior high school students received supplemental education in 2017, with an average cost of around 5,616 yuan ($870) per student.

The country's supplemental education industry is estimated to have exceeded 458 billion yuan in 2017.

The survey was conducted among 40,011 households in 29 provincial-level regions across China.