Year	Percent
1990	65.32
1991	66.36
1992	66.9
1993	66.93
1994	66.81
1995	66.43
1996	66.11
1997	65.78
1998	65.73
1999	66.57
2000	66.22
2001	65.77
2002	65.34
2003	65
2004	64.43
2005	64.02
2006	63.66
2007	63.64
2008	62.77
2009	61.04
2010	60.08
2011	60.79
2012	61.6
2013	62.55
2014	62.95
2015	63.22
2016	65.13
2017	66.22
2018	67.4
2019	67.6