Year	Percent
1990	73.81
1991	73.8
1992	73.84
1993	73.82
1994	73.76
1995	73.68
1996	73.68
1997	73.6
1998	73.51
1999	73.43
2000	73.38
2001	73.4
2002	73.39
2003	73.42
2004	73.37
2005	73.36
2006	73.47
2007	73.55
2008	73.61
2009	73.58
2010	73.5
2011	73.64
2012	73.67
2013	73.94
2014	73.82
2015	73.61
2016	73.37
2017	73.1
2018	72.8
2019	72.48