Year	Percent
1990	74.15
1991	74.21
1992	74.18
1993	74.11
1994	74.07
1995	74.18
1996	74.25
1997	74.3
1998	74.37
1999	74.41
2000	74.38
2001	74.37
2002	74.27
2003	74.11
2004	73.94
2005	73.81
2006	73.72
2007	73.65
2008	73.57
2009	73.46
2010	73.28
2011	73.2
2012	73.09
2013	72.95
2014	72.8
2015	72.64
2016	72.54
2017	72.46
2018	72.37
2019	72.27
2020	69.76