Year	Percent
1970	84.05467
1971	84.82143
1972	85.15284
1973	85.68376
1974	86.19247
1975	86.50307
1976	86.97395
1977	87.45098
1978	87.71593
1979	88.15789
1980	88.76611
1981	89.16968
1982	89.73451
1983	90.12132
1984	90.64626
1985	91
1986	91.33987
1987	91.82692
1988	92.2956
1989	92.60401
1990	93.04085
1991	93.47181
1992	93.87755
1993	94.27754
1994	94.66292
1995	95.03448
1996	95.39295
1997	95.74468
1998	96.07843
1999	96.40565
2000	96.84343
2001	97.1464
2002	97.558
2003	97.83914
2004	98.11098
2005	98.37398
2006	98.74286
2007	98.98763
2008	99.33555
2009	99.56379
2010	99.89259
2011	100.21164
2012	100.52138
2013	100.8222
2014	101.01317
2015	101.2987