The Pew Research Center has released a new report, The Rise of the Nones, on the changing shape of American religion.
Protestants are down by 5% to 48% total.
Religiously unaffiliated (nones) are up 5% to 20%.
Catholics are down 1% to 22%
Other religions are up 2% to 6%.
The main thing that seems to have happened is that lightly affiliated Protestants of five years ago now no longer call themselves religious at all.