That’s basically the findings of this Gallup survey from 2009. While the article itself focuses on the anomaly of religious belief in rich world America; it was this table that for me as a missionary to Sweden, caught my interest.
“On the opposite end of the spectrum, the 10 least religious countries studied include several with the world’s highest living standards, including Sweden, Denmark, Norway, Hong Kong, and Japan. (Several other countries on this list are former Soviet republics, places where the state suppressed religious expression for decades.)”
Which just demonstrates the scale of the task ahead of us as well as the size of the opportunity!