A man holds a rosary as he prays near Notre-Dame Cathedral in Paris, France April 16, 2019. (Yves Herman/Reuters)

The Wall Street Journal is publishing a series of reports to end the year, looking back at the last decade of life in the United States from a number of angles. In one of its latest entries, Ian Lovett examines the way that Americans’ affiliation with institutional religions has declined from 2010 to now.

The number of Americans who call themselves Catholics or who are affiliated with a non-Christian faith has remained fairly steady over the last decade, but the percentage of Protestants has declined sharply, while the percentage of Americans who describe themselves as “unaffiliated” has risen. Here’s what Lovett notes after sorting through the data:

Protestant denominations were hardest hit. At the start of the 2010s, 51% of American adults identified as Protestant, according to the Pew Research Center. Now, the number sits at 43%, based on telephone surveys in 2018 and 2019. The latest number is in keeping with a trend line for Christianity in the U.S. that has pointed sharply downward over the past 10 years. Christians make up 65% of the adult population, according to Pew, down from 76% at the start of the decade. Regular church attendance has taken a similar dive.

At the same time, nearly 10 percent more adults today say they are part of no religious group — from 17 percent in 2010 to 26 percent today — and Millennials are the least religious of any cohort. The decline in religiosity, and Christian affiliation, seems to have taken place slowly over the course of the last few generations. While more than 80 percent of the Silent Generation still identifies as Christian, only about 50 percent of Millennials do, and more than 40 percent of Millennials say they are unaffiliated with any religious tradition.