| 2014 | Democratic | 508,807 | 41.1% | | | Republican | 726,821 | 58.8% | | | Other | 1,514 | 0.1% | |
| 2010 | Democratic | 596,620 | 44.8% | | | Republican | 735,089 | 55.2% | | | Other | 1,012 | 0.1% | |
| 2006 | Democratic | 540,306 | 49.8% | | | Republican | 543,414 | 50.1% | | | Other | 1,372 | 0.1% | |
| 2002 | Democratic | 498,431 | 45.8% | | | Republican | 573,734 | 52.7% | | | Other | 15,901 | 1.5% | |
| 1998 | Democratic | 494,021 | 46.5% | | | Republican | 555,214 | 52.2% | | | Other | 14,154 | 1.3% | |
| 1994 | Democratic | 416,030 | 45.4% | | | Republican | 489,419 | 53.4% | | | Other | 10,403 | 1.1% | |
| 1990 | Democratic | 440,844 | 58.8% | | | Republican | 309,038 | 41.2% | | | Other | 469 | 0.1% | |
| 1986 | Democratic | 374,329 | 50.5% | | | Republican | 360,420 | 48.6% | | | Other | 6,519 | 0.9% | |
| 1982 | Democratic | 440,863 | 66.8% | | | Republican | 219,073 | 33.2% | | | Other | 134 | 0.0% | |
| 1978 | Democratic | 399,226 | 65.1% | | | Republican | 214,217 | 34.9% | | | Other | 242 | 0.0% | |
| 1974 | Democratic | 272,493 | 52.7% | | | Republican | 239,317 | 46.3% | | | Other | 4,894 | 0.9% | |
| 1970 | Democratic | 254,745 | 53.3% | | | Republican | 216,190 | 45.2% | | | Other | 7,320 | 1.5% | |
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