From opiates to amphetamines, the United Nations' latest watchdog report covers global consumption of illegal narcotics. The data reveal some surprises -- and one big puzzle.

If you had to guess the country that ranks the highest for marijuana usage in the world, which one would you say? You might be tempted to name a state in Europe, or in Latin America. But according to new United Nations data, the country with the highest share of its population on pot isn't in either region. It's the tiny Micronesian island of Palau. Who knew?

Nearly a quarter of all citizens used marijuana there in the last year, the UN says. The data are part of an annual report by the UN Office on Drugs and Crime that tracks drug use patterns worldwide. Coming after Palau on marijuana are some other unlikely suspects: the Northern Mariana Islands, followed by Guam. The United States ranks seventh in the world, with only 14 percent of its adults getting high on pot.

The Guardian's data journalism team turned the UN's statistics into a fascinating interactive feature that breaks down the results by narcotic as well as by country. Check it out:

Other interesting findings: The Isle of Man ranks the highest for cocaine usage, of all places, at 3.5 percent of the population aged 15-64. In the United States, marijuana remains the most popular narcotic by far, followed by cocaine (with 2.2 percent of adults using), amphetamines (1.8 percent), Ecstasy (1.2 percent), and opiates (0.6 percent).

But there's one big headscratcher, too: somehow, Iceland is considered the deadliest state for drug users, with 220 drug-related deaths per million people. Given that the country has just over 300,000 citizens to begin with, that means more than 700 Icelanders perished as a result of drugs last year (some 883, by the UN's count) that figure seems improbably high for a country with generally extraordinary life expectancy, especially when you consider how few Icelanders indulge in drugs: just 3.4 percent use cannabis and less than one percent were on any of the other drugs last year.

In fairness to Iceland, the UN dataset is somewhat incomplete. Out of the 224 territories examined, data on drug deaths exists for only 84. But although that helps explain Iceland's ranking -- there may be other states that beat it out for the unenviable title -- that still doesn't tell us why Iceland in particular suffers from such a high rate of drug deaths, particularly when drug use is so low. I've reached out to UNODC officials, and I'll post again with an update if and when there's anything to report.

Update: A UNODC spokesperson confirms that Iceland's drug-related death rate is in fact 220 per million, a figure you get when you divide the absolute number of deaths recorded in 2007 (45) by the country's population that year (203,885 -- or 0.2 million). It seems The Guardian may have incorrectly calculated its ranking by dividing the death rate by the population number, resulting in what appeared to be a high number of recorded deaths. The Guardian's released a new and updated version of its chart with a separate tab broken out for drug-related deaths by country per million. The new graphic also fills in some of the missing data points with information from older reports.
