The dominating U.S. population of Protestants and other non-Catholic Christians that dates back to Plymouth Rock has fallen below 50 percent for the first time, dipping to 49 percent amid a quick rise in those with no religious affiliation, according to a new survey.

The latest General Social Survey from the University of Chicago, a primary survey used by sociologists, found that those who belong to no church, so-called “Nones,” rose to 21 percent in 2014, doubling in just 20 years as Protestants have dropped from nearly 60 percent over the same period.