Year	Percent
1991	88.101
1992	86.434
1993	87.419
1994	87.095
1995	85.961
1996	86.97
1997	86.016
1998	86.144
1999	85.663
2000	84.734
2001	84.343
2002	83.994
2003	84.134
2004	84.354
2005	83.96
2006	84.145
2007	83.701
2008	83.586
2009	83.453
2010	83.255
2011	83.103
2012	82.99
2013	82.626
2014	82.589
2015	82.637
2016	82.284
2017	82.245
2018	82.206
2019	82.167
2020	82.127
2021	82.088
2022	82.048