Year	Percent
1991	80.348
1992	80.76
1993	80.793
1994	80.736
1995	80.444
1996	80.246
1997	80.022
1998	79.631
1999	79.319
2000	79.068
2001	78.448
2002	77.854
2003	77.221
2004	76.547
2005	76.121
2006	75.778
2007	75.623
2008	74.809
2009	74.567
2010	74.29
2011	73.962
2012	73.658
2013	73.388
2014	73.111
2015	72.836
2016	72.535
2017	72.251
2018	71.882
2019	71.468
2020	71.031
2021	70.563
2022	70.067