Here is a summary of how many chart-toppers the Idols have racked up:

Kelly Clarkson 45
Carrie Underwood 31
Chris Daughtry (Daughtry) 20
Fantasia 20
Ruben Studdard 15
Clay Aiken 11
Kimberley Locke 7
Josh Gracin 6
Mandisa 6
Taylor Hicks 3
Elliott Yamin 3
American Idol Finalists 2
Bo Bice 2
David Cook 2
Paris Bennett 1
Bucky Covington 1
Diana DeGarmo 1
Tamyra Gray 1
William Hung 1
Jennifer Hudson 1
Kellie Pickler 1

http://www.billboard.com/bbcom/chart_beat/bonus.jsp