Year	Percent
1991	66.233
1992	65.669
1993	65.594
1994	65.835
1995	65.484
1996	65.251
1997	64.716
1998	64.612
1999	64.583
2000	64.161
2001	63.772
2002	63.539
2003	63.501
2004	62.806
2005	62.714
2006	62.263
2007	61.905
2008	61.444
2009	61.691
2010	61.424
2011	60.853
2012	60.598
2013	60.357
2014	60.046
2015	59.816
2016	59.751
2017	59.721
2018	59.675
2019	59.647
2020	59.604
2021	59.561
2022	59.514