Year	Percent
1990	62.68
1991	63.15
1992	63.56
1993	63.97
1994	64.43
1995	64.91
1996	65.35
1997	65.72
1998	65.68
1999	65.86
2000	66.01
2001	66.12
2002	65.32
2003	65.32
2004	65.25
2005	65.64
2006	66.38
2007	67.15
2008	68.23
2009	68.26
2010	68.83
2011	69.12
2012	69.81
2013	69.85
2014	70.62
2015	71.38
2016	71.09
2017	70.98
2018	70.63
2019	70.51
2020	69.64