Year	Percent
1976	94.39861
1977	94.18437
1978	94.21851
1979	94.07733
1980	94.08118
1981	94.01176
1982	93.76159
1983	93.62649
1984	93.70554
1985	93.87751
1986	94.11287
1987	93.96191
1988	93.77499
1989	93.72755
1990	93.72583
1991	93.67237
1992	94.08955
1993	94.04308
1994	93.65438
1995	93.77317
1996	93.7654
1997	93.83661
1998	94.06633
1999	94.2902
2000	94.06912
2001	94.14805
2002	94.30325
2003	94.18723
2004	94.24037
2005	94.39247
2006	94.32394
2007	94.43907
2008	94.69017
2009	94.61259
2010	94.68182
2011	94.75288
2012	94.65261
2013	94.66916
2014	94.85026
2015	94.97885
2016	95.08096
2017	94.95349