Efforts to help smokers kick the habit have stalled in the United States, with hardly any recent change in smoking rates, federal researchers reported on Thursday.

Just over 20 percent of the adult population smoked in 2008, according to the U.S. Centers for Disease Control and Prevention, and 1,000 people take up the habit every day.

Overall smoking prevalence did not change significantly from 2007 to 2008, CDC researchers wrote in the weekly report on death and disease.

In 2008, an estimated 20.6 percent (46 million) of U.S. adults were current cigarette smokers; of these, 79.8 percent (36.7 million) smoked every day, and 20.2 percent (9.3 million) smoked some days.

Just over 45 percent of current smokers reported they had tried to quit at least once in the past year.

The CDC's Ann Malarcher and colleagues analyzed data from the 2008 National Health Interview Survey of 21,781 adults,

Between 1998 and 2008, the number of smokers fell by 3.5 percent, from 24.1 percent to 20.6 percent, with almost all that decline before 2005.

Smokers tended to have less education, the survey found.

Only 5.7 percent of people advanced graduate degrees smoked while 27.5 percent of people with less than a high school diploma did so.

More than 41 percent of people who had a General Educational Development certificate, which means they never formally graduated from high school but later passed a test, were smokers.

Smokers were defined as having smoked at least 100 cigarettes in their lifetimes and current smokers were defined as smoking every day or nearly every day.

Congress gave the U.S. Food and Drug Administration the power this year to regulate tobacco.

Legislators in states with high smoking rates must redouble their efforts to increase tobacco excise taxes, use that money to fund comprehensive programs to prevent children from starting to use tobacco and help current smokers quit, American Heart Association chief executive officer Nancy Brown said in a statement.

They must also enact smoke-free workplace laws that include all workplaces, restaurants and bars, she said.

The American Cancer Society says tobacco use remains the single largest preventable cause of disease and premature death in the United States and says cigarettes account for about 443,000 premature deaths every year, including 49,400 in nonsmokers.

A study published earlier this month found that smokers who switch to a low-tar, light or mild brand of cigarette will not find it easier to quit and in fact may find it harder.

And a report from the Institute of Medicine found that indoor smoking bans lower the risk of heart attack, even among nonsmokers, by reducing exposure to secondhand smoke.

Addiction