Year	Percent
1990	78.37
1991	78.06
1992	77.76
1993	77.46
1994	77.15
1995	76.85
1996	76.55
1997	76.24
1998	75.94
1999	75.64
2000	75.33
2001	75.03
2002	74.72
2003	74.42
2004	74.12
2005	73.81
2006	73.47
2007	73.13
2008	72.79
2009	72.45
2010	72.11
2011	72.11
2012	72.11
2013	72.11
2014	72.11
2015	72.11