Year	Percent
1990	64.86
1991	65.07
1992	63.29
1993	63.98
1994	64.67
1995	64.67
1996	65.41
1997	66.1
1998	68.31
1999	70.01
2000	70.95
2001	70.79
2002	70.85
2003	71.1
2004	71.46
2005	73.77
2006	74.64
2007	75.25
2008	74.6
2009	72.93
2010	71.63
2011	71.23
2012	71.24
2013	71.97
2014	72.08
2015	72.28
2016	72.85
2017	72.91
2018	73.23
2019	73.51