Like the rest of the United States, teens' tobacco use has been generally declining over the years. But right now, e-cigarettes are on the rise in high schools, according to just-released CDC data.

Every year, the CDC conducts a National Youth Tobacco Survey, a questionnaire, and the results from the 2013 survey of 20,000 students are in. The number of high school students who said they've used an e-cigarette in the last 30 days was 4.5 percent, up from 2.8 percent in the last year's survey, which itself was up from 1.5 percent the year before that. The percentage who said they'd tried e-cigs for the first time was also up, to 12 percent compared with last year's 10 percent. About 46 percent of the students said they'd used tobacco in some form in their lifetimes.

For middle schoolers, also questioned, the number who said they'd used e-cigarettes in the past month was flat at 1.1 percent, although the number of students trying them for the first time slightly increased from 2.7 percent to 3 percent. Cigar and cigarette use declined slightly for both groups, but overall tobacco use stayed about flat.

The FDA is in the middle of finalizing new rules for e-cigarettes that would ban their sale to anyone under 18 and require ID for purchase.