Year	Percent
1991	67.997
1992	67.941
1993	67.577
1994	67.268
1995	66.962
1996	66.752
1997	66.665
1998	66.344
1999	66.104
2000	65.702
2001	65.596
2002	65.526
2003	43.273
2004	43.38
2005	43.113
2006	43.164
2007	42.568
2008	42.212
2009	41.93
2010	42.023
2011	41.363
2012	40.715
2013	40.086
2014	36.726
2015	35.38
2016	32.593
2017	32.715
2018	32.591
2019	32.493
2020	32.357
2021	32.209
2022	32.061