Year	Percent
1991	60.137
1992	60.049
1993	60.006
1994	59.96
1995	60.043
1996	60.003
1997	59.89
1998	59.894
1999	59.883
2000	59.878
2001	59.831
2002	59.801
2003	59.755
2004	59.71
2005	59.699
2006	59.71
2007	59.734
2008	59.75
2009	59.743
2010	59.726
2011	59.724
2012	59.679
2013	59.319
2014	59.105
2015	58.936
2016	59.055
2017	59.131
2018	59.2
2019	59.268
2020	59.338
2021	59.451
2022	59.576