@pzmyers What caused the sudden rise of the "no religion" affiliation in the early 1990s?
Maybe the internet made it more acceptable for the non-religious to come out of the closet?
Sometimes these affiliations are a product of how the statistics are done: http://www.24oranges.nl/2013/12/22/ietsism-or-how-the-dutch-invented-a-new-belief-system/ (disclosure: self-promotion).
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