Year	Percent
1990	59.21
1991	59.25
1992	59.4
1993	59.56
1994	60.84
1995	58.58
1996	58.44
1997	58.24
1998	57.99
1999	58.58
2000	60.79
2001	62.37
2002	60.36
2003	60.7
2004	61.03
2005	61.3
2006	61.49
2007	63.02
2008	61.9
2009	62.62
2010	63.01
2011	63.16
2012	63.33
2013	63.56
2014	63.86
2015	61.77
2016	60.96
2017	60.16
2018	59.65
2019	59.64