What percentage of high school kids do you think smoke weed?

I have two friends who both recently found out their teenage sons smoke weed. Both don’t live near each other, each household is a two parent household, average income, both families live in fairly affluent areas. Both families are far apart on the political spectrum – one is very Republican, and one is very liberal.

When both of my friends told me the stories of how they found out the two different sons from two different families smoke marijuana, the sons each said “Everyone does it.”

Because each is different but they have that one thing in common, I am wondering if everyone does do it, like they said. What percentage of high school kids actually do smoke weed. Can you hazard a guess?