Worldwide illegal drug use estimated at 200 million people a year

Between 149 million and 271 million people worldwide used an illicit drug at least once in 2009, according to a new review of studies attempting to estimate the extent of the problem. That translates to 1 in 20 people aged 15 to 64 taking an illegal drug.

But this global figure is likely to underestimate the number of users, the researchers warn, since people might not want to admit to illegal use in surveys, and data from the poorest countries is limited.