Year	Percent
1990	72.63
1991	72.79
1992	74.94
1993	77.44
1994	79.5
1995	80.44
1996	80.24
1997	79.67
1998	78.76
1999	78.08
2000	77.14
2001	75.15
2002	73.24
2003	71.43
2004	69.59
2005	68.4
2006	66.98
2007	66.18
2008	65.15
2009	64.77
2010	64.56
2011	64.15
2012	64.27
2013	64.54
2014	65.05
2015	65.52
2016	66.26
2017	66.59
2018	66.84
2019	66.5
2020	63.13