Study leader Louisa Degenhardt of the University of New South Wales in Sydney and colleagues said the study is is based on the World Health Organization's Composite International Diagnostic Interview.

The study, published in PLoS Medicine, found that 16.2 percent of people in the United States had used cocaine in their lifetime, with the second highest level of cocaine use in New Zealand, where 4.3 percent reporting having used cocaine. U.S. marijuana use was highest in at 42.4 percent, followed by New Zealand at 41.9 percent.

Countries with more stringent policies towards illegal drug use did not have lower levels of such drug use than countries with more liberal policies. In the Netherlands, which has more liberal drug policies than the United States, 1.9 percent of people reported cocaine use and 19.8 percent reported marijuana use.

In the Americas, Europe, Japan, and New Zealand, alcohol had been used by the vast majority of survey participants, compared to smaller proportions in the Middle East, Africa, and China.