Year	Percent
1990	62.46
1991	62.72
1992	62.92
1993	63.13
1994	63.31
1995	63.44
1996	63.54
1997	63.6
1998	63.66
1999	63.72
2000	63.8
2001	63.96
2002	64.63
2003	65.32
2004	66.01
2005	66.71
2006	67.39
2007	67.94
2008	68.33
2009	68.6
2010	68.79
2011	69.22
2012	69.69
2013	70.21
2014	70.73
2015	71.23
2016	71.7
2017	72.16
2018	73.22
2019	72.45
2020	69.4