Forget Colorado or Washington — tiny Rhode Island is the marijuana capital of the United States, at least as measured by the percent of state residents who regularly use marijuana.

Map: Marijuana use by state

State-level statistics from the latest National Survey on Drug Use and Health (rather unfortunately acronymed NSDUH) show that just over 1 in 8 Rhode Island residents over age 12 smoke marijuana monthly. This is more than three times the rate in Kansas, where only 4 percent of residents regularly indulge.

Nationally about 7 percent of Americans over age 12 have used marijuana in the past month. Western states tend to have the highest rate of usage, at 9 percent, followed by the Northeast. The South has the lowest overall rate at 5.83 percent.

In what will surely not be a surprise to anyone who has ever been young, 18- to 25-year-olds use marijuana the most. Nearly 19 percent of that group has used marijuana in the past month, according to the NSDUH. But again, the state-to-state variation in those numbers are considerable. More than one third of Vermonters in that age bracket regularly use marijuana, compared to less than 10 percent of Utah's 18- to 25-year-olds.

But usage rates drop off considerably for people age 26 and older: Only 5 percent of Americans in that age group smoke marijuana regularly. Alaska's 26-and-over crowd is the most likely to regularly use marijuana, at 11.18 percent. To put it another way, Alaska's adults are more likely to use marijuana than Utah's college-age crowd.

Both Oregon and Alaska have marijuana legalization measures on their ballots this fall. Not coincidentally, these are the two states with the highest rates of 26-and-over marijuana use.

See the full state-level data below, and check out the rest of Wonkblog's coverage of the marijuana legalization debate.