About 18 percent of Americans had anxiety disorders, versus 12 percent of the French, 11 percent of Lebanese and 10 percent of Colombians. Europeans other than the French were in the 7 percent range, while Nigerians and Chinese were the calmest, at about 3 percent.

The findings were based on 60,643 face-to-face interviews with adults in 14 countries. Eight countries were defined as rich: the United States, Germany, France, Italy, Belgium, Spain, the Netherlands and Japan; six were deemed poor or nearly poor: Mexico, Colombia, Ukraine, China, Lebanon and Nigeria. Within each country, whether rich or poor, the study took into account the economic status of respondents.

For example, about 26 percent of Americans were judged to have mental illness, compared with only 4 percent of the residents of Shanghai and 5 percent of Nigerians.

The differences were even more extreme in smaller categories. The Dutch were found to have 30 times the drinking problems that Italians had, and 4 times the problem of the French.

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