Year Percent 2000-01-01 73.5 2001-01-01 67.5 2002-01-01 62.3 2003-01-01 57 2004-01-01 60.2 2005-01-01 51 2006-01-01 76.2 2007-01-01 74.6 2008-01-01 92.1 2009-01-01 100.4 2010-01-01 92.5 2011-01-01 94.6 2012-01-01 97.1 2013-01-01 99.8 2014-01-01 98.9 2015-01-01 99.0