Year	Percent
1990	55.95
1991	56.17
1992	56.89
1993	57.14
1994	58.54
1995	59.05
1996	58.53
1997	58.2
1998	58.48
1999	58.63
2000	58.51
2001	57.95
2002	58.84
2003	58.75
2004	56.81
2005	58.11
2006	58.5
2007	59.38
2008	59.66
2009	59.98
2010	59.96
2011	60.02
2012	60.29
2013	60.43
2014	60.16
2015	60.1
2016	60.51
2017	60.52
2018	60.73
2019	60.78
2020	59.91