A Pew Research Center poll published Tuesday indicates that the number of people in the U.S. who describe themselves as religiously unaffiliated increased by 6 points in the last five years and 10 points in the last decade. 

When asked about their religious identity, 29 percent of respondents, or about 3 in 10 U.S. adults, said they had "none," meaning they were atheists, agnostics or “nothing in particular,” according to the Pew Research Center survey.  

“If the unaffiliated were a religion, they’d be the largest religious group in the United States,” Elizabeth Drescher, an adjunct professor at Santa Clara University, told The Associated Press.

Drescher said that the religiously unaffiliated previously resided mostly in urban and coastal communities but now are spread across the country.

Christians, including Protestants, Catholics, members of the Church of Jesus Christ of Latter-day Saints and Orthodox Christians, still make up a majority of the U.S. population, the survey indicates

Specifically, they account for 63 percent of the adult population, a 12 percentage point decrease compared to data from 2011. 

While the percentage of Catholic U.S. adults has remained relatively steady, accounting for about 21 percent of the population since 2014, the population of Protestant adults declined to 40 percent this year, down 4 points in the last five years.

Less than half of respondents, 45 percent, report praying once a day, compared to 58 percent in a 2007 survey.

The Pew survey included 3,937 respondents and was conducted from May 29 to Aug. 25. It has a margin of error of plus or minus 2.1 percentage points.