Sept. 2002:23

Oct. 2002:27

Nov. 2002:27

Jan. 2003:14

Feb. 2003:35

July 2004:24

Sept. 2004:18

Jan. 2006:10

Aug. 2006:16

July 2007:17

Sept. 2007:9

Dec. 2007:11

Jan. 2009:5

Jan. 2010:26

Feb. 2010:18

May 2011:21

Source: New York Times/CBS News poll