http://www.pewforum.org/2016/05/12/changing-attitudes-on-gay-marriage/
Changing Attitudes on Gay Marriage
In Pew Research Center polling in 2001, Americans opposed same-sex marriage by a margin of 57% to 35%. Since then, support for same-sex marriage has steadily grown. Based on polling in 2016, a majority of Americans (55%) support same-sex marriage, compared with 37% who oppose it. See the latest data on same-sex marriage.
www.pewforum.org