In a study entitled “Global Index of Religion and Atheism” — a survey of over 50,000 respondents in 57 countries conducted in 2012 — WIN-Gallup International researchers showed a negative correlation between “religiosity” and per capita income based on responses to the question: “Irrespective of whether you attend a place of worship or not, would you say you are a religious person, not a religious persons or a convinced atheist?”

Comparing the responses across nations, it appears that countries with lower per capita incomes tended to have higher levels of self-reported religiosity, and as per capita income increases, reported religiosity decreases. Interestingly, while the United States ranks among the highest in terms of per capita income, more than half of American respondents still reported themselves as being a religious person.

Globally, the study found that there was a rise in people responding as not religious or as atheist compared to the previous survey in 2005, a trend that includes the United States.

See the entire study here.