There have been about 120,000 same-sex marriages since they were legalized nation-wide last year. The total number of marriages in 2014 was 2.1 million. So, assuming similar stats for the previous year, the percentage of gay weddings would be just over 5%.
How many pastors have been asked to perform gay weddings? According to a new study, 11%. Presbyterians were asked most often (26%), followed by Lutherans (19%), but I’m pretty sure these would be the liberal denominations in those traditions–the PCUSA, not the PCA; the ELCA, not the LCMS. Only 1% of Baptist pastors were asked, so gay weddings seem to be largely taking place among mainline liberal protestants.
Of course, same-sex couples are unlikely to ask pastors from churches that don’t recognize gay marriages, which is logical, and they don’t seem to want to make trouble in their weddings, usually asking pastors whom they know.