Columns: Season | Episodes | Time slot (EST) | Season premiere | Season finale | TV season | Rank | Viewers (in millions)
1 | 23 | Wednesday 10pm/9c | September 22, 2004 | May 18, 2005 | 2004–2005 | #21 | 13.59 | 2 | 24 | Wednesday 10pm/9c | September 28, 2005 | May 17, 2006 | 2005–2006 | #22 | 14.04 | 3 | 24 | Wednesday 10pm/9c | September 20, 2006 | May 16, 2007 | 2006–2007 | #25 | 13.92 | 4 | 21 | Wednesday 10pm/9c | September 26, 2007 | May 21, 2008 | 2007–2008 | #28 | 11.71 | 5 | 25 | Wednesday 10pm/9c | September 24, 2008 | May 14, 2009 | 2008–2009 | #17 | 13.50 | 6 | 23 | Wednesday 10pm/9c | September 23, 2009 | May 26, 2010 | 2009–2010 | #23 | 12.66 | 7 | 22 | Friday 9pm/8c | September 24, 2010 | May 13, 2011 | 2010–2011 | #37 | 10.73 | 8 | 18 | Friday 9pm/8c | September 23, 2011 | May 11, 2012 | 2011–2012 | #38 | 10.34