Year Measure 1995 2.79 1996 3.33 1997 3.06 1998 3 1999 3.2 2000 3.2 2001 3.2 2002 3.2 2003 3.3 2004 3.6 2005 3.8 2006 3.6 2007 3.3 2008 3.5 2009 3.4 2010 3.5 2011 3.381