This would indicate your numbers are way high.
http://oas.samhsa.gov/NSDUH/2k10NSDUH/t ... tm#Tab1.1B
Table 1.1B – Types of Illicit Drug Use in Lifetime, Past Year, and Past Month among Persons Aged 12 or Older: Percentages, 2009 and 2010
Lifetime (2009) 47.1%
Lifetime (2010) 47.1%
Past Year (2009) 15.1%
Past Year (2010) 15.3%
Past Month (2009) 8.7%
Past Month (2010) 8.9%
Table 1.6B – Types of Illicit Drug Use in Lifetime, Past Year, and Past Month among Persons Aged 21 to 25: Percentages, 2009 and 2010
Lifetime (2009) 61.3%
Lifetime (2010) 59.8%
Past Year (2009) 34.6%
Past Year (2010) 33.2%
Past Month (2009) 20.5%
Past Month (2010) 20.5%
Table 1.8B – Types of Illicit Drug Use in Lifetime, Past Year, and Past Month among Persons Aged 35 or Older: Percentages, 2009 and 2010
Lifetime (2009) 45.5%
Lifetime (2010) 45.4%
Past Year (2009) 8.4%
Past Year (2010) 8.8%
Past Month (2009) 4.9%
Past Month (2010) 4.9%
It is also important to consider that lifetime data is a reflection of national cultural curves for the periods lived. And, as each age group progresses forward it takes its history with it. So with this in mind, for example, one would expect a higher lifetime percentage for an age group that was "of age" during the 60's and 70's than say a group that was "of age" in the 40's and 50's.Illicit Drugs include marijuana/hashish, cocaine (including crack), heroin, hallucinogens, inhalants, or prescription-type psychotherapeutics used nonmedically.
In any event, Simon, where did you get your numbers?