Unlike Record of the Year, which goes to the performer and production team of a single song, Song of the Year goes to the composer(s) of the song.
|2008 - Amy Winehouse for "Rehab" performed by Amy Winehouse|
|2007 - Martie Maguire, Natalie Maines, Emily Robison, and Dan Wilson for "Not Ready To Make Nice" performed by Dixie Chicks|
|2006 - U2 for "Sometimes You Can't Make It On Your Own"|
|2005 - John Mayer for "Daughters"|
|2004 - Richard Marx and Luther Vandross for "Dance with My Father" performed by Luther Vandross|
|2003 - Jesse Harris for "Don't Know Why" performed by Norah Jones|
see the rest of the 50 years here