Despite the steady decline in the percentage of Americans who identify as Christian, the proportion of congressional members who say they are Christian has remained very close to what it was in the early 1960s, according to a new report.

The report, released on Tuesday by Pew Research Center, found that 91 percent of the members of the new session of Congress, the 115th, identified as Christian. More than half a century ago, in 1961, 95 percent of United States representatives and senators said that they were Christian, the report said.

As the report notes, an analysis of the General Social Survey, a survey of Americans that has been taken regularly since 1972, suggests that the percentage of Christians among the United States population is declining, particularly among young adults.

In a phone interview on Tuesday, Aleksandra Sandstrom, the report’s author, said that the steadiness of Congress’s religious composition was striking given the broader change in the country’s population.