The American National Election Studies conducts periodic research on the opinions of U.S. voters. The accompanying table shows the percentage of people, in selected years from 1952 to 2012, who agreed with the statement “There are important differences in what the Republicans and Democrats stand for.” What do these data say about the degree of partisanship in U.S. politics over time?

Agree with statemen Year t 1952 50%

1972 46 1992 60 2004 76 2008 78 2012 81 Data from: American National Election Studies.