Year	Percent
1990	68.78
1991	70.49
1992	72.18
1993	73.83
1994	75.47
1995	75.21
1996	75.01
1997	74.84
1998	74.69
1999	74.48
2000	74.16
2001	73.72
2002	73.22
2003	72.7
2004	72.2
2005	71.71
2006	71.19
2007	70.67
2008	70.15
2009	69.62
2010	69.09
2011	68.59
2012	68.08
2013	67.53
2014	66.91
2015	66.21
2016	65.5
2017	64.73
2018	63.93
2019	63.86