[crz]

How many times in the last 40 years has Iowas winner gone on to win the whole thing?

Not that many.

[deport]

Now that you asked........

Candidates in bold eventually won their party's nomination. Candidates also in
italics subsequently won the general election.

Iowa Caucuses

• 2012 - Rick Santorum (25%), Mitt Romney (25%), Ron Paul (21%), Newt Gingrich (13%), Rick Perry (10%), Michele Bachmann (5%), and Jon Huntsman (0.6%)^[14]
• 2008 Mike Huckabee (34%), Mitt Romney (25%), Fred Thompson (13%), John McCain (13%), Ron Paul (10%), Rudy Giuliani (4%), and Duncan Hunter (1%)
• 2004 George W. Bush (unopposed)
• 2000 George W. Bush (41%), Steve Forbes (31%), Alan Keyes (14%), Gary Bauer (9%), John McCain (5%), and Orrin Hatch (1%)
• 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%)
• 1992 George H. W. Bush (unopposed)
• 1988 Bob Dole (37%), Pat Robertson (25%), George H. W. Bush (19%), Jack Kemp (11%), and Pete DuPont (7%)
• 1984 Ronald Reagan (unopposed)
• 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%)
• 1976 Gerald Ford (45%) and Ronald Reagan (43%)