Year	Percent
1990	65.92
1991	63.68
1992	61.26
1993	61.15
1994	61.46
1995	59.16
1996	59.57
1997	59.65
1998	63.42
1999	61.55
2000	60.6
2001	60.5
2002	60.43
2003	60.37
2004	60.3
2005	60.2
2006	60.13
2007	60.01
2008	59.86
2009	59.68
2010	58.48
2011	58.25
2012	57.46
2013	59.13
2014	58.48
2015	59.47
2016	59.76
2017	59.9
2018	57.93
2019	57.52