The Institute for Social Research at the University of Michigan periodically conducts the World Values Survey. It polls a statistically valid sample of adults from a total of 60 nations. Some of their findings from their 1995-1997 survey:

The United States has a higher level of church attendance than any other country which is “at a comparable level of development.”

53% of Americans consider religion to be very important in their lives. This compares with 16% in Britain, 14% in France and 13% in Germany. The importance of religion has been declining in developed countries.

In those countries which are “experiencing economic stagnation and political uncertainty,” the importance of religion is high.

Political scientist Ronald Inglehart, one of the authors of the Institute’s 1998 survey commented: “Although church attendance is declining in nearly all advanced industrial societies, spiritual concerns more broadly defined are not. In fact, in most industrial societies, a growing share of the population is spending time thinking about the meaning and purpose of life.”

from http://www.religioustolerance.org/rel_rate.htm