Fewer U.S. adults are smoking, a new government report says.
Last year, about 18 percent of adults participating in a national health survey described themselves as current smokers.
The nation's smoking rate generally has been falling for decades, but had seemed to stall at around 20 to 21 percent for about seven years.
In 2011, the rate fell to 19 percent, but that might have been a statistical blip.
Health officials are analyzing the 2012 findings and have not yet concluded why the rate dropped, a spokesman for the Centers for Disease Control and Prevention said. The CDC released its study Tuesday.
Smoking is the leading cause of preventable illness and death in the United States. It's responsible for the majority of lung cancer deaths and is a deadly factor in heart attacks and a variety of other illnesses.
Concerned about the stalled smoking rate, the CDC launched a graphic advertising campaign last year that was the agency's largest and starkest anti-smoking push. The campaign triggered an increase of 200,000 calls to quit lines, and CDC officials said thousands of smokers probably went on to kick the habit. The CDC did a second wave of the ads earlier this year.