Year	Percent
1991	85.434
1992	86.201
1993	85.994
1994	86.22
1995	86.111
1996	85.006
1997	85.784
1998	85.31
1999	85.543
2000	84.483
2001	83.26
2002	82.803
2003	81.138
2004	80.198
2005	79.943
2006	80.847
2007	82.119
2008	82.817
2009	83.626
2010	81.934
2011	80.933
2012	80.298
2013	80.941
2014	81.001
2015	82.894
2016	82.321
2017	82.338
2018	82.292
2019	82.221
2020	82.155
2021	82.091
2022	82.028