Year Percent 1991 66.66 1992 65.915 1993 66.483 1994 66.41 1995 65.754 1996 65.828 1997 63.533 1998 64.656 1999 64.698 2000 64.421 2001 64.419 2002 60.131 2003 60.155 2004 62.027 2005 62.113 2006 62.575 2007 62.354 2008 63.784 2009 63.272 2010 63.338 2011 62.881 2012 60.243 2013 60.123 2014 60.047 2015 60.387 2016 61.064 2017 61.111 2018 61.061 2019 61.012 2020 60.962 2021 60.914 2022 60.867