I wonderabout those figures and how much weighting there is from peer pressure and fear of deviating from the norm. A 2008 poll for example, "One-fifth of the U.S. public – and a third of adults under 30 – are religiously unaffiliated today, the highest percentages ever in Pew Research Center polling."
Yes you're right. Most are "unaffilliated." However the polls are done anoymously so I don't see peer pressure entering into it. Being "uaffiliated" with a particular church is a long way from being "un-religious." And those anonymous polls have more that 87% of the population identifying themselves as religious. Rather like you say some people might well go to church due to peer pressure bu that doesn't make them religious; likewise NOT going to or JOINING any particular church (also often due to peer pressure) doesn't make them unreligious. Over here, religion is often a private thing. Although I'll grant there are indeed a good number of hypocrites.
If you go to "Sperlings Best Places" online you can get a breakdown by individual cities showing complete demographics: Religious affilliation, voter habits, crime rates, ethnicity, average age, etc. As well as climate and number of doctors per population and teachers per student, average salary, percentage of home ownership, cost of living compared to the national average, tax base and rates, etc. However as I believe Sperling's gets their info (on religious afflliation) from registered church memberships, it just might show bias from peer pressure.