Year	Percent
1990	72.41
1991	72.39
1992	72.36
1993	72.51
1994	72.45
1995	72.45
1996	72.51
1997	72.52
1998	72.5
1999	72.53
2000	72.56
2001	72.54
2002	72.52
2003	72.44
2004	72.2
2005	72.04
2006	72.06
2007	72.02
2008	71.95
2009	71.85
2010	71.66
2011	71.62
2012	71.49
2013	71.36
2014	71.21
2015	71.07
2016	71.06
2017	70.99
2018	70.86
2019	70.72