Year	Percent
1990	57.62
1991	57.9
1992	58.09
1993	58.23
1994	58.34
1995	58.43
1996	58.45
1997	58.44
1998	58.43
1999	58.4
2000	58.37
2001	58.35
2002	58.32
2003	58.3
2004	58.3
2005	58.32
2006	58.35
2007	58.39
2008	58.44
2009	58.51
2010	58.63
2011	58.77
2012	58.93
2013	58.95
2014	59.05
2015	59.08
2016	59.19
2017	59.25
2018	59.28
2019	59.28
2020	57.22