Year	Percent
1991	82.502
1992	82.608
1993	82.54
1994	82.182
1995	81.364
1996	79.773
1997	77.951
1998	75.341
1999	78.642
2000	78.042
2001	75.437
2002	75.989
2003	74.073
2004	70.222
2005	66.236
2006	65.191
2007	64.232
2008	63.196
2009	62.743
2010	61.702
2011	60.582
2012	59.829
2013	60.054
2014	59.558
2015	55.913
2016	53.681
2017	53.656
2018	53.551
2019	53.45
2020	53.356
2021	53.262
2022	53.174