Year Measure 1995 2.7 1996 2.96 1997 3.56 1998 4 1999 4.1 2000 3.9 2001 4 2002 4 2003 3.9 2004 3.9 2005 3.7 2006 3.3 2007 3.5 2008 3.5 2009 3.7 2010 3.7 2011 3.77411