Year	Percent
1970	82.53478
1971	83.1307
1972	83.70703
1973	84.26471
1974	84.94935
1975	85.47009
1976	86.11501
1977	86.8603
1978	87.3297
1979	88.05369
1980	88.62434
1981	89.17862
1982	89.83269
1983	90.48223
1984	91.10276
1985	91.83168
1986	92.42054
1987	93.11594
1988	93.67542
1989	94.33962
1990	94.87179
1991	95.61707
1992	96.34703
1993	96.83973
1994	97.5419
1995	98.01105
1996	98.47328
1997	98.81593
1998	99.25611
1999	99.58071
2000	100
2001	100.40858
2002	100.70565
2003	100.99502
2004	101.27701
2005	101.64888
2006	101.81818
2007	102.0794
2008	102.33427
2009	102.67528
2010	102.82332
2011	103.06031
2012	103.29181
2013	103.42707
2014	103.649
2015	103.86598