Environmental and social shareholder proposals are gaining greater voting support from investors at U.S. public companies, according to a recently released survey by the Investor Responsibility Research Center Institute (IRRCi).

From 2005-2011, average support for these proposals more than doubled, from about 10 percent to more than 20 percent. During that same time period, the proportion of shareholder-sponsored resolutions on environmental and social matters grew by a third, from about 30 percent to 40 percent of all proposals going to a vote.