Year	Percent
1991	80.75
1992	81.079
1993	80.191
1994	80.485
1995	80.086
1996	80.16
1997	80.186
1998	79.738
1999	79.769
2000	79.06
2001	78.373
2002	78.07
2003	77.735
2004	78.28
2005	78.569
2006	80.189
2007	80.316
2008	79.809
2009	79.43
2010	79.53
2011	79.083
2012	78.782
2013	78.409
2014	78.706
2015	78.871
2016	80.24
2017	80.062
2018	79.914
2019	79.766
2020	79.577
2021	79.353
2022	79.101