I don't have the data on that, but I can tell you that there is evidence out there—particularly from the state where Dr. Shackelford is working and some other jurisdictions—good papers reporting on the reduction of pharmaceutical sales and presumably the use of pharmaceutical products in jurisdictions where the state moved to legalizing medical cannabis. In other words, there's evidence that people, when using cannabis, will stop using their prescription hypnotics, sedatives, painkillers and the like.
On March 20th, 2019. See this statement in context.