Indoor tanning is on the decline among U.S. high school students, but many teen girls are still participating in the potentially dangerous practice.

The recent study shows 20 percent of high school females engaged in indoor tanning at least once in 2013, and about 10 percent tanned fairly regularly, the JAMA Network Journals reported.

Indoor tanning is known to increase the risk of cancer when done often and from a young age. To make their findings the researchers looked at data on high school students from 2009, 2011 and 2013 national Youth Risk Behavior Surveys.

"The surveys included 16,410 students in 2009, 15,425 in 2011 and 13,583 in 2013; overall response rates were 71 percent, 71 percent and 68 percent, respectively," the researchers reported.

The findings showed 20.2 percent of high school students engaged in indoor tanning in 2013 and 10.3 percent engaged in frequent indoor tanning (classified as using a tanning device 10 times or more over a period of 12 months).  Tanning was most prevalent in non-Hispanic white high school females.

Among male high school students, 5.3 percent engaged in indoor tanning and 2 percent engaged in frequent indoor tanning.

Between the years of 2009 and 2013 tanning was found to have decreased from 25.4 percent to 20.2 percent in female students, from 37.4 percent to 30.7 percent in non-Hispanic white girls, and from 6.1 percent to 3.2 percent in non-Hispanic black males.

"These decreases in indoor tanning may be partly attributable to increased awareness of its harms. Despite these reductions, indoor tanning remains common among youth," the study concluded.

The findings were published Dec. 23 in the journal JAMA Dermatology. The study was conducted by Gery P. Guy Jr., Ph.D., M.P.H., of the U.S. Centers for Disease Control and Prevention, Atlanta, and coauthors.