The share of Americans calling themselves Christians has dropped sharply in recent years, according to a new Pew Research Center survey — while the population of religiously unaffiliated adults has risen.

Though more Christians call America home than any other country, the percentage of American adults identifying as Christians has fallen from 78.4% in 2007 to about 70.6%. Meanwhile, over one in five (22.8%) say they are unaffiliated with any faith, a 6.7% percentage point jump since 2007.

Pew finds the Millennial generation is leading the decline in religious affiliation, though adults of all ages and across all demographic groups are steering away from Christianity. About 36% of Americans between 18 and 24 claim to be religiously unaffiliated, along with some 34% of Americans between 24 and 33.

Protestants and Catholics experienced the greatest drop in population, according to the survey, with populations declining respectively by 5 and 3 million people. There has, however, been a bump in the number of Evangelical Christians in the U.S.—Pew estimates that population has grown by 2 million since 2007.

The survey is Pew’s second to examine the religious landscape of America. The survey seeks to fill a gap left by the Census, which does not question Americans’ religious affiliation. A little over 35,000 adults were interviewed for the survey, which has a margin of error of 0.6 percentage points.

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