Year	Percent
1990	67.46
1991	67.2
1992	66.89
1993	66.54
1994	66.14
1995	65.68
1996	65.22
1997	64.71
1998	64.19
1999	63.71
2000	63.28
2001	63.41
2002	63.6
2003	63.85
2004	64.13
2005	64.43
2006	64.69
2007	64.96
2008	65.23
2009	65.52
2010	65.78
2011	66.08
2012	66.38
2013	66.67
2014	66.95
2015	67.2
2016	67.46
2017	67.7
2018	67.93
2019	68.14
2020	64.58