>Given 1/6 adults admit to using it

That seems high to me. (sorry) ;-)

Seriously though, by the time I was 15 several of my classmates were drunk most weekends and smoked cigarettes regularly, but even decades later I have still never seen or heard of anyone I know smoking weed. That's why it sticks out so much to me.

If 1/6 is true it would be interesting to see how it has changed over the past say 20 years or so.

I think cigarettes and alcohol were established vices when media became a thing so media can be semi-excused from those. It would be interesting to know if the same is true for weed. Has it just gotten so common that media has to show it to be realistic, or did it get more common after media started to show it?

Cigarette smoking is an interesting counterexample, it has been extremely de-glamorized since the heydays and sales of cigarettes have halved since 2000.