How often did Carl Sagan smoke marijuana?

It is well know (among some communities) that Carl Sagan, eminent astronomer and populizer of science, was a total pothead.

But how often did he smoke weed? Once a week? Once a day? Several times a day?

The only reference I could find to Sagan’s frequency of use is in his masterful essay about the joys of smoking pot, where he says, “Through the years I find that slightly smaller amounts of cannabis suffice to produce the same degree of high, and in one movie theater recently I found I could get high just by inhaling the cannabis smoke which permeated the theater.”

And I’m not really sure how to interpret this. He also says “I find that today a single joint is enough to get me high.” To my eyes, that seems to be a lot to get high. So together these two statements could imply that Carl Sagan has smoked so much pot that he is no longer even building up a tolerance to it. But that still doesn’t even answer how often he smoked.

Like space, a grand and glorious mystery.