Wiki says it increased usage for 2 centuries after it became prohibited. "Opium prohibition in China began in 1729, yet was followed by nearly two centuries of

Wiki says it increased usage for 2 centuries after it became prohibited. "Opium prohibition in China began in 1729, yet was followed by nearly two centuries of increasing opium use." https://en.wikipedia.org/wiki/Opium https://en.wikipedia.org/wiki/Opium Don't know if we can trust numbers from that time though, you probably want to look at production.