Year	Percent
1970	87.25637
1971	87.75811
1972	88.22674
1973	88.69814
1974	89.01408
1975	89.58333
1976	89.87688
1977	90.2834
1978	90.81225
1979	91.1958
1980	91.56939
1981	91.93342
1982	92.40506
1983	92.75
1984	93.07787
1985	93.51285
1986	93.93939
1987	94.35774
1988	94.64923
1989	94.92925
1990	95.31616
1991	95.58653
1992	96.0739
1993	96.32606
1994	96.6895
1995	97.04545
1996	97.3064
1997	97.78024
1998	97.91895
1999	98.37662
2000	98.61111
2001	98.94515
2002	99.27083
2003	99.58848
2004	99.89848
2005	100.2006
2006	100.49505
2007	100.78201
2008	100.96525
2009	101.23928
2010	101.50659
2011	101.76744
2012	101.92837
2013	102.2686
2014	102.51121
2015	102.74823