The survey was conducted every year from 1972 to 1994 (except in 1979, 1981, and 1992). Since 1994, it has been conducted every other year. The website gives access to the data itself, as well as survey documentation, reports on methodological issues & uses of the data, quick downloads (by year), a bibliography and information on the variables.
A unique, rich data source for US public opinion topics. It includes 650,000 questions and answers from 1935 through last week, gathered from all the major polling organizations in the country (Gallup, Harris, Pew, etc.)