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Estimate of the percentage of the population using marijuana annually, using data from the most recent year available. Ranges from nearly 0% (Singapore 2004 and Japan 2017) to almost 30% (Papua New Guinea and Micronesia, 1995).

I used this UNODC dataset for most countries, but for the minority of countries not covered there I grabbed older estimates from a 2006 UNODC report. The most recently available year with data varies from 1995 to 2019, but the median is 2012.