Year	Percent
1990	72.02
1991	72.85
1992	73.66
1993	74.41
1994	75.06
1995	75.16
1996	75.16
1997	75.11
1998	75.05
1999	74.98
2000	74.9
2001	75.05
2002	75.17
2003	75.19
2004	75.13
2005	75.07
2006	75.22
2007	75.33
2008	75.34
2009	75.3
2010	75.29
2011	75.26
2012	75.34
2013	75.43
2014	75.54
2015	75.62
2016	75.66
2017	75.66
2018	75.64
2019	75.61
2020	71.74