Total Opium Production
It is widely accepted that drug use is a natural human behavior. But modern governments try to eliminate this behavior when it comes to drugs that they have decided they don't like. The table below shows that, as important as opium is as a medical agent, it is far more important as a recreational agent. Five times as much opium is used illegally (for recreational purposes) as legally (for medical purposes). It is certainly true that the laws probably limit the amount of opium used medically, but this is also true of the opium used recreationally. This division (five to one), is probably about what we would see without government involvement.
The PART column represents the percentage of all opium that is produced legally.