It looks like vaping may have turned out to be a trend whose time has come and gone, at least among teenagers. A Centers for Disease Control and Prevention survey out yesterday (June 15th) found that teen vaping, which had been soaring, plummeted last year in the U.S. The survey suggests that the number of high school and middle school students using electronic cigarettes dropped to 2.2 million last year from 3 million the year before. It’s too soon to know if the numbers will continue to decline, and it’s unclear why there was such a big drop last year. However, factors could include the growing effort to ban e-cigarette sales to minors, the influence of ad campaigns to discourage kids from vaping, and e-cigarettes may be losing their novelty.