The number of American adult smokers has declined by about 1.5 percent, or 3 million people, from 2005 to 2010, according to a new report from the Centers for Disease Control and Prevention. But the rate of decline has not been consistent year-to-year.

The report finds out that form 2005 to 2010, the proportion of smokers declined from 20.9 percent to 19.3 percent.

The report comes as the Food and Drug Administration announced new regulations that will require tobacco companies to present additional warnings on the front of tobacco products. The law is calling for larger, graphic warning labels on cigarette packs starting September 2012.

The federal report released Tuesday said that despite national efforts to raise tobacco taxes, increase awareness of cigarettes' health risks, and bans on smoking in public places, the decline in smoking rates over the past five years has slowed dramatically.

The 2005-2010 National Health Interview Surveys and the 2010 Behavioral Risk Factor Surveillance System survey were used to estimate national and state adult smoking prevalence, respectively.      

While the percentage of adults who smoke 30 or more cigarettes per day is down by 4 percent, the percentage of those who smoke nine or fewer cigarettes a day has increased from 16.4 percent in 2005 to 22 percent in 2010.

Health officials stress that even light smokers face health problems like heart disease, lung cancer, and strokes. Fifty percent of adults who continue to smoke will die from smoking-related causes, the report said.

While the results represent progress, more needs to be done in order to combat health risks posed by smoking, said CDC Director Dr. Tom Frieden.

Smoking costs the U.S. $193 billion per year in healthcare costs and lost productivity, and it remains the single largest preventable cause of disease, disability, and death in the U.S., the researchers said.

Every year the tobacco industry spends almost $10 billion on advertising and 72 percent of these dollars are spent on discounts to offset the costs of tobacco taxation and other policies, researchers said.

Tobacco use and exposure to secondhand tobacco smoke kill an estimated 443,000 Americans each year.

The CDC said states need to step up their tobacco control policies.