What America's Users Spend on Illegal Drugs 1988-2000 - National ...

Number of Marijuana <strong>Users</strong>More Americans use marijuana than either cocaine or heroin. During 1999, for example, about 11.9 millionAmericans used marijuana or hashish at least once in the month before the NHSDA. This number is somewhatgreater than it was in 1988 (11.0 million). The trend was for decreasing use into the early 1990s and thenincreasing use into the late 1990s.Reports from the Community Epidemiology Work Group provide confirmation for the trends presented here.The five reports between June 1999 and June 2001 suggest that marijuana use had been increasing until theend of the decade, at which point use stabilized and may have started to decrease. Our trend estimates, whichare based entirely on the NHSDA, also suggest that marijuana use increased through much of the 1990s.Marijuana use may have stabilized toward the end of the decade, but the NHSDA does not show that marijuanause has begun to decrease.Average Number of Joints Used Each MonthWe calculated an individual’s total number of joints used each month by multiplying the number of days ofmarijuana use in the past month by the number of joints used per occasion. For those without valid answersfor these questions, we imputed the total monthly use. 42 In 1995 the NHSDA stopped asking respondentsabout the number of joints and amount of marijuana used in the last month. Because marijuana users reportedusing an estimated 18.7 joints per month in 1994, we assumed the same was true for the years after 1994.Average Amount of Marijuana UsedThe average amount of marijuana used in the past month was calculated from several questions in the survey. 43This number has changed little over time – about 0.014 ounces per joint. However, the average number andweight of joints used by those who smoke marijuana cannot tell the entire story about trends in marijuana usebecause marijuana’s THC content has changed over time. Delta-9 tetrahydrocannabinol (THC) is marijuana’sprimary psychoactive chemical. According to a continuing study to monitor THC content conducted at theUniversity of Mississippi, 44 during the 1990s the average THC content of commercial grade marijuanaincreased from about 4 percent to about 5.5 percent. The THC content of sinsemilla increased from about 824