Year	Percent
1990	58.25
1991	59.63
1992	59.01
1993	58.33
1994	58.53
1995	58.19
1996	57.96
1997	58.15
1998	58.13
1999	58.32
2000	58.06
2001	57.96
2002	57.85
2003	57.9
2004	57.59
2005	58.45
2006	58.84
2007	59.19
2008	59.21
2009	59.35
2010	59.43
2011	60
2012	59.94
2013	60.24
2014	60.24
2015	60.08
2016	60.32
2017	60.51
2018	60.83
2019	61.25
2020	60.57