September 1999	September 2000
November 1999	March 2001
March 2000	September 2001
June 2000	November 2001
November/December 2002	March 2002
March 2003	September 2002
November 2004	September 2004
September 2005	March 2005
June 2006	September 2007
March 2008	June 2008
September 2008	November 2008
March 2009	June 2009
September 2009	November 2009
March 2010	June 2010