Year	Percent
1990	75.66
1991	75.64
1992	75.78
1993	75.84
1994	75.82
1995	75.81
1996	75.66
1997	75.08
1998	74.87
1999	74.71
2000	74.41
2001	74.52
2002	74.59
2003	74.97
2004	75.02
2005	75.11
2006	75.23
2007	75.33
2008	75.45
2009	75.54
2010	75.55
2011	75.53
2012	75.46
2013	75.33
2014	75.23
2015	75.09
2016	76.76
2017	76.54
2018	76.32
2019	76.13
2020	72.74