Scientific American
Originally published on October 20, 2017
Since 1990, the fraction of Americans with no religious affiliation has nearly tripled, from about 8 percent to 22 percent. Over the next 20 years, this trend will accelerate: by 2020, there will be more of these "Nones" than Catholics, and by 2035, they will outnumber Protestants.
The following figure shows changes since 1972 and these predictions, based on data from the General Social Survey (GSS):
