Year	Percent
1970	88.77551
1971	89.22156
1972	89.64844
1973	90.05736
1974	90.6367
1975	91.19266
1976	91.38241
1977	92.07746
1978	92.41379
1979	92.8934
1980	93.3665
1981	93.65854
1982	94.09888
1983	94.52269
1984	94.77727
1985	95.03012
1986	95.4142
1987	95.78488
1988	96
1989	96.34831
1990	96.54696
1991	96.875
1992	97.05882
1993	97.23684
1994	97.27979
1995	97.32143
1996	97.35849
1997	97.39454
1998	97.42962
1999	97.46377
2000	97.61621
2001	97.64982
2002	97.79582
2003	97.82609
2004	97.85553
2005	98.10479
2006	98.23982
2007	98.37134
2008	98.49946
2009	98.62434
2010	98.74739
2011	98.96907
2012	98.98271
2013	99.29648
2014	99.40476
2015	99.60784