Last year, the CDC report showed a decline in teen vaping, but this year, that decline is no longer evident.

One in five high school students use some form of tobacco, and new e-cigarette products appear to be enticing millions of young people.

The CDC's annual National Youth Tobacco Survey finds that overall usage is down since 2011.

However, 3.6 million middle and high school students report smoking or chewing some form of tobacco.

E-cigarettes are the most popular form of tobacco among teenagers.

Last year, the CDC report showed a decline in teen vaping, but this year, that decline is no longer evident.

E-cigarette usage appears to have leveled off, and experts say new products that have hit the market may be to blame.

Brian King of the CDC's office on smoking and health said, "Within the past year we've seen an increase reports of youth use of a USB-shaped e-cigarette called Juul, which is increasingly popular. So it's likely that this lack of change that we've seen in the past year is a result of these new e-cigarette products. So we really need to remain diligent in terms of monitoring the patterns in future years to come."

Juul labs has taken steps to deter usage of its products among kids and teens.