Year Percent 1995-01-01 77 1996-01-01 77 1997-01-01 77 1998-01-01 74 1999-01-01 74 2000-01-01 73 2001-01-01 76 2002-01-01 80 2003-01-01 78 2004-01-01 77 2005-01-01 77 2006-01-01 80 2007-01-01 80 2008-01-01 79 2009-01-01 79 2010-01-01 79 2011-01-01 76 2012-01-01 83 2013-01-01 78