According to the Pew Foundation’s latest report, about 20% of Americans claim to have no religious affiliation.  This is said to be a gain of 5% over the last five years.

Before celebrating too much, note that the associated graph still shows self-described atheists at about 3% of the population and agnostics at about twice that.  These numbers also have to be taken with a huge grain of salt because they are reporting on how people describe themselves, which does not have much to do with what they actually are.