You might think economic prosperity and a high standard of living would make you happy, but it turns out it can be pretty depressing.

A new study incorporating interviews with more than 89,000 people in 18 nations revealed that 15 percent of people in high-income countries reported having been depressed, compared with 11 percent of those in low- or middle-income countries. Depression rates were highest in the United States and France, eclipsing poorer countries like Mexico.

Researchers interpreted the data as reflecting a difference in expectations, positing that the rich-poor discrepancy stemmed from situational depression rather than clinical depression, which is likely to be longterm and have its roots in biological factors.

"There are a lot of people in the U.S. who say they aren't satisfied with their lives," Kessler, a professor of health care policy at Harvard Medical School, told Bloomberg. "U.S. expectations know no bounds and people in other countries are just happy to have a meal on the table."'

Another theory is that wealthier countries tend to be more socially fragmented and individualistic, with the pursuit of a career often taking precedence over family or spirituality.

"Wealthier nations ... are industrialized nations where individuals rely less on family support for everything from childcare to marital advice," Dr. Sudeepta Varma, an assistant professor of psychiatry at New York University's Langone Medical Center, told ABC. "There is a well known link between social support being a protective factor against depression."

While rates varied from country to country, depression had the capacity to impair a person's quality of life in every country. Women also registered nearly double the depression rates of men, something that researchers linked to the dissolution of a relationship through divorce or the death of a spouse.

Compiling data on depression could prove to be less controversial than trying to quantify happiness. Britain's attempt to measure average levels of happiness has drawn skepticism from people who believe there is no objective way to do so, and critics assailed Bhutan's Gross National Happiness Index as a propaganda tool.