The report, published yesterday in JAMA, tracked the prevalence of heavy smokers (defined as people who smoke 20 cigarettes or more, per day) among more than a million-and-a-half respondents between 1965 and 2007.
Researchers from the University of California San Diego found that in 1965 -- the year after the first-ever surgeon general's report on smoking and health -- 56 percent of people who identified as smokers were heavy, or pack-a-day, smokers. By 2007, that percentage dropped dramatically, to only 40 percent.
