Year	Percent
1990	58.73
1991	58.71
1992	58.69
1993	58.83
1994	58.46
1995	58.18
1996	57.9
1997	57.57
1998	57.57
1999	57.52
2000	57.59
2001	57.71
2002	57.79
2003	57.83
2004	58.03
2005	58.31
2006	58.53
2007	58.82
2008	59.02
2009	59.16
2010	59.26
2011	59.34
2012	59.37
2013	59.38
2014	59.34
2015	59.27
2016	59.19
2017	59.09
2018	58.96
2019	58.81
2020	57.32