Year	Percent
1991	75.599
1992	75.316
1993	74.876
1994	74.387
1995	74.153
1996	73.822
1997	73.677
1998	73.624
1999	73.397
2000	72.92
2001	72.514
2002	71.85
2003	71.022
2004	70.211
2005	69.538
2006	68.961
2007	68.446
2008	67.975
2009	67.518
2010	67.111
2011	66.678
2012	66.272
2013	65.908
2014	65.539
2015	65.157
2016	64.879
2017	64.971
2018	65.054
2019	65.133
2020	65.194
2021	65.238
2022	65.281