The prevalence of cigarette use among U.S. public high school seniors has reached the lowest point ever recorded, according to the most recent data from the national Monitoring the Future survey.

Slightly more than one-fifth (21.6%) of 12th graders reported smoking cigarettes in the past thirty days, down from peaks of 36.5% in 1997 and 38.8% in 1976.

At the same time, the percentage of students who perceived a ''great risk'' of harm from smoking one or more packs of cigarettes per day reached an all-time high of 77.6% in 2006.

Previous research has found that increases in perceived risk of using a drug are related to decreases in the use of the drug.