(HuffPost) – Weekly church attendance by American Catholics continues its decades-long decline, a new Gallup report shows.

About 39 percent of Catholics reported attending church in any given week, according to data collected between 2014 and 2017 and released Monday. That’s down from 45 percent between 2005 and 2008. And it’s a huge drop from 1955 when Gallup polling reported weekly Mass attendance at 75 percent.

Even older Catholics, who are typically more religiously committed than younger ones, have stopped going to church as often. For the first time, Gallup found that no more than 49 percent of Catholics in any age group reported attending church in the past week.

“Given that young Catholics are even less devout, it appears the decline in church attendance will only continue,” wrote Lydia Saad, a senior editor at Gallup.

Attending Mass on Sundays is one of the five requirements laid out by the Roman Catholic Church as a minimum for leading a Christian life. In 1955, many Catholics of all ages fulfilled this obligation, according to Gallup. But Mass attendance declined rapidly through the 1970s and has continued to decrease at a slower pace since then. Gallup reports that Mass attendance stabilized briefly in the mid-2000s, before resuming a “downward trajectory” over the past decade.

Gallup’s survey also analyzed the attendance rates of Protestants, which it defined as all denominations of that branch of Christianity along with anyone who chose the generic term “Christian” to describe themselves. The pollster found that the number of Protestants who said they attended church within the past seven days has remained relatively stable since 1955. Protestant youth are more likely than Catholic youth ― 36 percent to 25 percent ― to say they’ve attended church in any given week.

While their rate of church attendance has remained steady, however, the percentage of Americans identifying as Protestants has declined sharply, from 71 percent in 1955 to 47 percent between 2014 and 2017.

On the other hand, the percentage of Americans who identify as Catholics has remained relatively stable ― 24 percent in 1955 and 22 percent in the latest polling. Gallup suggests this overall stability is largely a result of the growth of the Hispanic Catholic population.

Gallup’s results are based on data aggregated from multiple nationally representative surveys conducted near the middle of each decade from the 1950s through the present.

Mark M. Gray, who directs Catholic polling at Georgetown University’s Center for Applied Research in the Apostolate, told HuffPost that his team’s surveys indicate an even lower rate of weekly attendance for Catholics. (He suggested CARA’s surveys may do a better job at working around people’s bias toward giving socially desirable answers.)

Gray estimates that Mass attendance declined from about 62 percent in 1958 to about 30 percent today in any given week, other than those containing Ash Wednesday, Easter and Christmas. CARA’s research indicates that the percentage of Catholics attending Mass has remained relatively steady since 2000.

Narrowing the data to look at only those who say they go to Mass every week results in an even bleaker picture, according to CARA. Just 22 percent of Catholics describe themselves as regular weekly attendees today.

Gray said that people who attend Catholic churches don’t necessarily notice this decline on the ground.

“It depends on which ground you are viewing from,” he said. “There have been Catholic population losses in the Northeast and Midwest and gains in the South and West. In the former, they are closing and consolidating parishes and in the latter, they are trying to build bigger facilities with more parking.”

“Currently, the Catholic population is not well aligned with the brick and mortar of parishes,” Gray said.

Beyond Mass attendance, Gray said there are other trends that are even more worrisome for the Catholic Church ― including declines in baptisms, church marriages and adults who were raised Catholic continuing to identify as Catholic.