May 24, 2016 -- The smoking rate among American adults fell from 17 percent in 2014 to 15 percent in 2015, the largest one-year decline in more than 20 years, the Centers for Disease Control and Prevention said Tuesday.
The smoking rate has been declining for decades, but typically falls one percent or less in a year, the Associated Press reported.
The last time there was a larger-than-normal decrease was between 1992 and 1993, when the rate dropped 1.5 percent, said the CDC's Brian King.
The reasons for the 2 percent decline between 2014 and 2015 are unclear, and whether there will be another significant drop this year is uncertain, the AP reported.
Smoking is the leading cause of preventable illness in the U.S. and causes more than 480,000 deaths a year, according to the CDC.