(RNS) One in 10 U.S. churches employs a woman as senior pastor, double the percentage from a decade ago, according to a new survey by the Barna Group.

Most of the women — 58 percent — work in mainline Protestant churches, such as the United Methodist Church, Evangelical Lutheran Church in America, and Episcopal Church; only 23 percent of male senior pastors are affiliated with mainline churches, the survey said.

The UMC and its forerunner has ordained women for five decades; the ELCA and its predecessor has for almost 40 years, and the Episcopal Church has ordained women since 1976.

Barna’s survey found that female pastors tend to be more highly educated than their male counterparts, with 77 percent earning a seminary degree, compared to less than two-thirds of male pastors (63 percent).

But male pastors still rake in larger incomes. The average compensation package for female pastors in 2009 is $45,300, Barna says, while males earn $48,600. The compensation gap has closed in the last decade, though, with females earning 30 percent more than they did in 1999, according to the survey.

Barna says the difference in pay rates may be attributable to congregation size. Churches with male pastors average 103 adults at Sunday worship, compared to 81 for female pastors.

The median age of female pastors rose from 50 to 55 in the last decade; male pastors’ median age rose from 48 to 52.

Barna conducted the study by interviewing 609 senior pastors and balancing the sample according to the distribution of Protestant churches in the continental U.S. The range of sampling error was between 1.8 and 4.1 percentage points, according to Barna.