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Figure 9.2 is titled "Past Month Marijuana Use among Persons Aged 18 to 25: 1971 through 2004." It is a line graph, where the horizontal axis represents the study year and the vertical axis represents the percentage using in the past month. There is a note below the graph that reads, "Data points represent surveys conducted since 1971. The 1971 through 1998 data are from NHSDA (PAPI), the 1999 through 2001 data are from NHSDA (CAI), and the 2002 through 2004 data are from NSDUH (CAI). The three series of NSDUH/NHSDA data use different methodologies and are not comparable with the other series. MTF data are estimates for 12th graders for 1976 through 2004 and average estimates for persons aged 19 to 24 for 1983 through 2003." The graph has a line for Monitoring the Future (MTF) estimates for 12th graders, a line for MTF data for persons aged 19 to 24, and a line for NSDUH data for persons aged 18 to 25, which is broken into three sections based on the methodology of the survey.

MTF shows that the rate of past month marijuana use among 12th graders was 27.1 percent in 1975. This increased to 33.7 percent in 1980, and then decreased to 11.9 percent in 1992. The rate of past month marijuana use increased again to 23.7 percent in 1997, and then decreased slowly to 19.9 percent in 2004.

MTF shows that the rate of past month marijuana use among persons aged 19 to 24 was 29.3 percent in 1982. This decreased to 13.6 percent in 1991, and then increased through 2003 to 19.9 percent.

Using PAPI questionnaires, NHSDA shows that the rate of past month marijuana use among persons aged 18 to 25 was 17.1 percent in 1971. This increased sharply to 27.8 percent in 1972, and then decreased to 25.0 percent in 1976. The rate increased again to 35.6 percent in 1979, and then decreased steadily to 12.0 percent in 1995. The rate in 1998 was 13.8 percent. Using CAI, NHSDA shows that the rate of past month marijuana use among persons aged 18 to 25 was 14.2 percent in 1999. This increased to 16.0 percent in 2001. Using CAI, NSDUH shows that the rate of past month marijuana use among persons aged 18 to 25 was 17.3 percent in 2002. This decreased slightly to 16.1 percent in 2004.

Back to Figure 9.2

This page was last updated on May 20, 2008.