Year	Percent
1991	71.77
1992	72.22
1993	72.91
1994	73.37
1995	73.78
1996	73.27
1997	73.07
1998	73.25
1999	73.71
2000	74.25
2001	73.64
2002	73.56
2003	73.99
2004	74.89
2005	76.11
2006	76.55
2007	77.65
2008	79.08
2009	80.63
2010	81.8
2011	81.7
2012	81.52
2013	81.35
2014	81.34
2015	81.57
2016	81.16
2017	80.28
2018	80.28
2019	80.15
2020	76.9