Republicans
1976: Gerald Ford (45%) and Ronald Reagan (43%)
1980: George H. W. Bush (32%), Ronald Reagan (30%), Howard Baker (15%), John Connally (9%), Phil Crane (7%), John B. Anderson (4%), and Bob Dole (2%)
1984: Ronald Reagan (unopposed) - incumbent
1988: Bob Dole (37%), Pat Robertson (25%), George H. W. Bush (19%), Jack Kemp (11%), and Pete DuPont (7%)
1992: George H. W. Bush (unopposed) - incumbent
1996: Bob Dole (26%), Pat Buchanan (23%), Lamar Alexander (18%), Steve Forbes (10%), Phil Gramm (9%), Alan Keyes (7%), Richard Lugar (4%), and Morry Taylor (1%)
2000: George W. Bush (41%), Steve Forbes (31%), Alan Keyes (14%), Gary Bauer (9%), John McCain (5%), and Orrin Hatch (1%)
2004: George W. Bush (unopposed) - incumbent
2008: Mike Huckabee (34%), Mitt Romney (25%), Fred Thompson (13%), John McCain (13%), Ron Paul (10%), Rudy Giuliani (4%), and Duncan Hunter (1%)
2012: Rick Santorum (25%), Mitt Romney (25%), Ron Paul (21%), Newt Gingrich (13%), Rick Perry (10%), Michele Bachmann (5%), and Jon Huntsman (0.6%)
'76, '96, and '00, Iowa got the winner correct
'84, '92, and '04, it was an unopposed incumbent
'80, '88, '08, and '12, they were "wrong", with the eventual winner placing 2nd, 3rd, 4th, and 2nd.
So let's drop the rest of the field, trounce Rubio, and have a decent race between two very good choices!!
(Seriously... Who here wouldn't relish the final several debates being just between Trump and Cruz, and maybe Rubio. That would be sooooo nice to watch!)