Year	Percent
1990	57.55
1991	57.51
1992	57.49
1993	57.59
1994	57.65
1995	56.78
1996	55.95
1997	55.2
1998	55.56
1999	55.9
2000	56.23
2001	56.55
2002	56.83
2003	57.07
2004	57.3
2005	57.54
2006	57.87
2007	58.2
2008	58.52
2009	58.84
2010	59.17
2011	59.53
2012	59.9
2013	62.56
2014	62.7
2015	62.55
2016	62.39
2017	61.33
2018	60.22
2019	60.59