Washington, DC: Three out of four illicit drug users in the United States are marijuana smokers, according to survey data released today by the Department of Health and Human Services.According to the department's annual "National Survey on Drug Use and Health," an estimated 19.5 million Americans currently use illicit drugs (as defined as use within the past month). Of these, 14.6 million - or 75 percent - self-identify as marijuana smokers.By comparison, only 2.3 million Americans reported using cocaine, approximately one million reported using LSD, and fewer than 120,000 said that they currently use heroin. In addition, an estimated 97...