Table 1:
Reported cannabis use in the past 30 days in California by grade and data source
| MTF Year | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 95% Confidence Interval on the Trend | |
| CA-HKS Period | 2005–2007 | 2006–2008 | 2007–2009 | 2008–2010 | 2009–2011 | Missing | 2011–2013 | Trend (2007–2013) | |
| NSDUH Period | 2006–2007 | 2007–2008 | 2008–2009 | 2009–2010 | 2010–2011 | 2011–2012 | 2012–2013 | ||
| CA-HKS Grade 7 | 4 | 5 | 6 | 6 | 6 | 7 | 0.44 | ||
| MTF Grade 8 | 6 | 5 | 7 | 9 | 10 | 9 | 7 | 0.51 | 0.12 – 0.89 |
| CA-HKS Grade 9 | 12 | 12 | 13 | 15 | 15 | 15 | 0.61 | ||
| MTF Grade 10 | 14 | 13 | 18 | 20 | 19 | 17 | 18 | 0.75 | 0.27 – 1.16 |
| CA-HKS Grade 11 | 16 | 18 | 19 | 20 | 21 | 24 | 1.26 | ||
| MTF Grade 12 | 21 | 23 | 20 | 14 | 24 | 29 | 28 | 1.29 | 0.39 – 2.26 |
| NSDUH Ages 12–17 | 6.81 | 6.88 | 7.70 | 8.60 | 9.43 | 8.83 | 7.80 | 0.31 | |
Note: Reported trend and confidence intervals are based on simulated data using prevalence proportions and standard errors reported by Miech et al. (2015)