Year Percent 1991 91.309 1992 90.399 1993 90.888 1994 90.463 1995 90.205 1996 88.934 1997 88.643 1998 87.875 1999 87.19 2000 90.198 2001 89.937 2002 89.39 2003 88.91 2004 89.14 2005 88.3 2006 87.323 2007 86.715 2008 85.936 2009 85.768 2010 84.373 2011 83.431 2012 84.952 2013 84.993 2014 84.811 2015 84.355 2016 83.275 2017 83.273 2018 83.203 2019 83.134 2020 83.065 2021 82.999 2022 82.935