Past month prevalence of marijuana use (ages 12+) 2001: US- 5.4%; Netherlands- 3.0%
US Department of Health and Human Services (HHS), Substance Abuse and Mental Health Services Administration, National Household Survey on Drug Abuse: Volume I. Summary of National Findings (Washington, DC: HHS, August 2002), p. 109, Table H.1.
Trimbos Institute, "Report to the EMCDDA by the Reitox National Focal Point, The Netherlands Drug Situation 2002" (Lisboa, Portugal: European Monitoring Centre for Drugs and Drug Addiction, Nov. 2002), p. 28, Table 2.1.
The rate of heroin addiction in the US is about twice as high as in the Netherlands:
"The number of [heroin] addicts in the Netherlands has been stable - at 25,000 - for many years. [about 0.17%]
Source: Netherlands Ministry of Justice, Fact Sheet: Dutch Drugs Policy, (Utrecht: Trimbos Institute, Netherlands Institute of Mental Health and Addiction, 1999),
http://www.minjust.nl:8080/a_beleid/fact/cfact7.htm
"There were an estimated 980,000 hardcore heroin addicts in the United States in 1999, 50 percent more than the estimated 630,000 hardcore addicts in 1992." [about 0.34% ]
--www.usdoj.gov/ndic/pubs07/794/heroin.htm
Based on those numbers, 3% was way too low.
I appreciate your research.