Here are the dated I have been using. They could probably be refined some though

1/1/2000 - 4/30/2005
5/1/2005 - 5/1/2006
5/2/2006 - 11/15/2006
11/16/2006 - 5/17/2007
5/18/2007 - 9/6/2007
9/7/2007 - 1/27/2008
1/28/2008 - 5/29/2008
5/30/2008 - 12/31/2008

Hope it helps