Year	Percent
1970	75.87065
1971	76.39903
1972	76.90476
1973	77.38928
1974	77.90433
1975	78.34821
1976	78.82096
1977	79.2735
1978	79.70711
1979	80.32787
1980	80.56112
1981	81.13949
1982	81.53846
1983	82.07547
1984	82.62477
1985	82.97101
1986	83.48135
1987	83.82609
1988	84.47099
1989	84.78261
1990	85.38588
1991	85.66828
1992	86.09795
1993	86.66667
1994	87.0624
1995	87.46269
1996	87.82991
1997	88.20144
1998	88.82603
1999	89.16667
2000	89.63165
2001	89.94638
2002	90.38208
2003	90.80311
2004	91.33758
2005	91.61452
2006	92.11823
2007	92.37288
2008	92.7381
2009	93.20047
2010	93.65629
2011	93.98411
2012	94.30168
2013	94.71947
2014	95.12459
2015	95.41089