This is what the Unitarians say about themselves.
http://www.uuworld.org/news/articles/183612.shtml
Membership in Unitarian Universalist congregations has fallen for the third consecutive year, with overall membership falling to 162,796 adults from 164,196. In addition, the number of congregations has declined to 1,046, with a net loss of two congregations last year.
Amid the downward-sloping statistics, however, the Rev. Peter Morales, president of the Unitarian Universalist Association, sees reason for optimism. Declines in UU membership have been slight. Declines in other denominations, including evangelical churches, however, have been precipitous. The evangelical slide is an amazing opportunity, he said, noting that opinion surveys on social issues, such as marriage equality, indicate that more people are aligned with UUA values. The culture is moving our way theologically, but not institutionally.
.................................................................................................................
Three of the UUAs 19 districts showed a net increase in members last year. The Joseph Priestley District, which includes congregations in Delaware, the District of Columbia, Maryland, and parts of New Jersey, Pennsylvania, and Virginia, posted the largest gain, of 91 members. The Massachusetts Bay District, which includes congregations in eastern Massachusetts, grew by 41 members. And the Pacific Central District, which serves northern California, northern Nevada, and Hawaii, grew by five.
Membership fell the most in the Central Midwest Districtwhich includes congregations in Illinois and parts of Indiana, Michigan, Missouri, and Wisconsinand the Southwestern UU Conference, which serves Arkansas, Louisiana, Oklahoma, Texas, and parts of Missouri and Tennessee. Each of these districts lost 224 members. The Metropolitan New York District, which includes congregations in parts of Connecticut, New Jersey, New York, and Pennsylvania, lost 186 members.
Here is the in-depth report.
http://www.uua.org/documents/administration/1104_morales_boardrpt.pdf