Year	Percent
1990	64.54
1991	64.78
1992	65.12
1993	65.91
1994	67.07
1995	68.04
1996	67.82
1997	67.68
1998	67.67
1999	68.04
2000	68.23
2001	68.02
2002	67.99
2003	67.66
2004	67.87
2005	68.22
2006	67.88
2007	67.86
2008	68.27
2009	69.37
2010	70.37
2011	70.96
2012	71.58
2013	72.34
2014	73.06
2015	73.7
2016	73.96
2017	74.54
2018	74.8
2019	74.97