Earlier quoted context omitted.
Does it count underage drinking? I didn't even notice that if it does. Regardless, around 85% of Americans use marijuana alone, so it wouldn't change the statistics by more than one or two percent. So I don't see how that would be misleading.
85% sounds pretty wild. Hm, looking at pg 78 of the linked document, it says among people surveyed who were exactly 50 years old when surveyed, graduating in 1977, those who tried marijuana were 82%. 1977 has got to have been the historical peak of high school usage. I notice they don't mention 51 year olds or 49 year olds, they have specifically pulled out this one exact age for this statistic. It then goes on to sa…
Only 50-year-olds are mentioned because this is a longitudinal cohort they've been testing since 1977, and this year (2009) it's their turn to be reported.
The "adjusted" number is higher than the measured number because some people answered the survey ten years ago saying they'd tried marijuana in the past year but then in the current survey the same respondent said "no" when asked if they'd ever tried marijuana in their lifetime. So they're publishing both the actual numbers and the "we know you're probably lying" numbers.