Not sure where you would find these statistics, but I did want to take a second to point out that the statistics are likely underrepresented. Many people don’t admit to doing illegal things, or admit to doing some fraction of their true answer, when someone asks them for a survey.
i know lots of people who have or do smoke pot, and none of them stopped after one time. so, i would say 98% of the people who try it once end up doing it again and usually again and again.