Year	Percent
1990	75.38
1991	75.02
1992	74.68
1993	74.33
1994	73.99
1995	74.26
1996	74.68
1997	74.86
1998	73.91
1999	72.68
2000	73.18
2001	72.54
2002	72.42
2003	72.34
2004	72.42
2005	72.53
2006	72.11
2007	72.7
2008	72.78
2009	72.86
2010	71.71
2011	73.24
2012	72.77
2013	70.69
2014	69.68
2015	69.05
2016	68.07
2017	67.29
2018	67.59
2019	66.74
2020	66.07