All Available Season All Season Season 1 Sep, 2003 23 episodes 8.0 Season 2 Oct, 2004 23 episodes 8.0 Season 3 Sep, 2005 23 episodes 8.1 Season 4 Sep, 2006 24 episodes 7.9 Season 5 Sep, 2007 18 episodes 7.1 Season 6 Sep, 2008 23 episodes 6.9 Season 7 Sep, 2009 22 episodes 7.3