Year Percent 1991 84.615 1992 84.615 1993 84.558 1994 84.526 1995 84.464 1996 84.496 1997 84.514 1998 84.478 1999 84.441 2000 84.693 2001 84.833 2002 83.593 2003 83.478 2004 83.679 2005 85.617 2006 87.181 2007 86.053 2008 85.155 2009 84.244 2010 82.637 2011 82.367 2012 86.072 2013 81.214 2014 82.372 2015 83.789 2016 83.045 2017 83.137 2018 83.215 2019 83.298 2020 83.412 2021 83.556 2022 83.716