Year	Percent
1991	73.97
1992	74.08
1993	74.1
1994	74.06
1995	74.05
1996	73.9
1997	73.34
1998	73.14
1999	72.96
2000	72.69
2001	72.8
2002	72.85
2003	73.22
2004	73.29
2005	73.41
2006	73.58
2007	73.73
2008	73.86
2009	73.85
2010	73.84
2011	73.84
2012	73.79
2013	73.68
2014	73.63
2015	73.53
2016	74.39
2017	74.25
2018	74.08
2019	73.93
2020	70.33