Year Percent 1993-01-01 36.4231 1994-01-01 37.0113 1995-01-01 31.5068 1996-01-01 23.9967 1997-01-01 25.8711 1998-01-01 21.6317 1999-01-01 18.2934 2000-01-01 17.3116 2001-01-01 16.6150 2002-01-01 16.3960 2003-01-01 16.7709 2004-01-01 18.7382 2005-01-01 21.0121 2006-01-01 24.6434 2007-01-01 29.3166 2008-01-01 36.9323 2009-01-01 42.1488 2010-01-01 42.4369 2011-01-01 43.5853 2012-01-01 46.0789 2013-01-01 45.2044 2014-01-01 46.1807 2015-01-01 47.8588 2016-01-01 46.9575