If the above is referencing the 1990 Doblin-Kleiman survey, the correct figure is 48%, not 70%.
The survey is so flawed as to be laughable. It was only mailed to some members of ASCO and less than half even responded.
Also, the survey was sponsored by the Alliance for Cannabis Therapeutics (ACT), a pro-marijuana advocacy group. Moreover, Mr. Doblin (who's taken so many LSD trips he has a passport), the senior author, is the president and founder of the Multidisciplinary Association for Psychedelic Studies (MAPS), whose main purpose is to help researchers secure federal approval and funding of studies of psychedelic drugs.