The United Nations estimated marijuana use around the world, and the United States ranks pretty high.
Not as high per capita as Iceland, where about a fourth of the population regularly uses the drug. But Iceland's a small country, so that's only about 55,000 people, which is less than the number of people smoking pot in the Gorge during a summer of concerts.
The map is based on data from 2012, so it predates legalization of recreational marijuana in Washington and Colorado. One other note: there's no data from big chunks of the world.