FILE - In this July 16, 2015 file photo, Bruce Schillin, 32, exhales vapor from an e-cigarette in Sacramento, Calif. In 2015, the rate of smoking among adults in the U.S. fell to 15 percent due to the biggest one-year decline in more than 20 years, according to a report by the Centers for Disease Control and Prevention released on Tuesday, May 24, 2016. The increased popularity of electronic cigarettes has likely played a role, but it is not yet clear whether this will help further propel the decline in smoking, or contribute to an increase in smoking in years to come. (AP Photo/Rich Pedroncelli, File)