Figure 10.1 is a line graph showing marijuana use among NSDUH youths aged 16 to 20 and MTF 12th graders for 1975-2002. The graph for lifetime marijuana for youths aged 16 to 20, based on NSDUH estimates, starts at 36.0 percent in 1975 and generally increases to 44.9 percent in 1979; it generally decreases to 29.7 percent for 1991 and then generally increases to 46.9 percent for 2001 and 45.8 percent for 2002. The graph for lifetime marijuana use for 12th graders, based on MTF estimates, is 47.3 percent in 1975 and generally increases to 60.3 in 1980; it then generally declines to 32.6 percent in 1992 and generally increases to 49.0 percent for 2001 and 47.8 percent for 2002. The graph for past month marijuana use for 12th graders based on MTF estimates is 27.1 percent for 1975 and generally increases to 37.1 for 1978, then generally decreases to 11.9 percent in 1991; from that point it moves to approximately 21 percent in 1995 and is between 21 and 23 percent until it reaches 22.4 percent for 2001 and 21.5 percent in 2002.