Year	Percent
1970	91.00346
1971	91.48695
1972	91.95531
1973	92.29923
1974	92.74106
1975	93.16969
1976	93.5857
1977	93.89234
1978	94.28571
1979	94.66801
1980	95.03968
1981	95.39667
1982	95.74879
1983	96.09152
1984	96.42185
1985	96.65428
1986	97.06152
1987	97.36842
1988	97.57848
1989	97.95918
1990	98.15789
1991	98.4375
1992	98.71134
1993	99.06383
1994	99.24179
1995	99.49917
1996	99.75166
1997	99.91797
1998	100.16273
1999	100.32258
2000	100.56
2001	100.79365
2002	100.94414
2003	101.17096
2004	101.31681
2005	101.45929
2006	101.67683
2007	101.81543
2008	101.95049
2009	102.15934
2010	102.21566
2011	102.34432
2012	102.47273
2013	102.5974
2014	102.72206
2015	102.84293