That is the study I was pointed to. If you did not realize that, then you are clearly not paying attention. Ah, yes, we have a symptom!
You've previously implicitly accepted that figure by citing it while questioning its "significance" (whatever it is you may mean by that). Since that blew up in your face, you're now backpedalling to questioning the figure. Well, here's another bomb: "Thirty-day marijuana use fell from 22 percent in 2011 to 20 percent in 2013, and lifetime use declined from 39 percent to 37 percent during the same two years." - https://www.colorado.gov/pacific/cdphe/news/news-new-survey-documents-youth-marijuana-use-need-prevention
That is the study I was pointed to.
So when you said, "I did a pretty thorough search starting at the CO site and came up empty" you forgot that you'd been pointed to the study? Ah, yes, we have a symptom!