Year	Percent
1970	93.39431
1971	93.69369
1972	94.077
1973	94.54722
1974	95
1975	95.35104
1976	95.69288
1977	96.11471
1978	96.52651
1979	96.84116
1980	97.14541
1981	97.53086
1982	97.90576
1983	98.18809
1984	98.46416
1985	98.81757
1986	99.16388
1987	99.50331
1988	99.7541
1989	100.08123
1990	100.40258
1991	100.71828
1992	100.94937
1993	101.17647
1994	101.4786
1995	101.69884
1996	101.83767
1997	102.12766
1998	102.26074
1999	102.46637
2000	102.59451
2001	102.72059
2002	102.84464
2003	102.96671
2004	103.08686
2005	103.20513
2006	103.25088
2007	103.4386
2008	103.48189
2009	103.59613
2010	103.63761
2011	103.74915
2012	103.7889
2013	103.83065
2014	103.93858
2015	103.97878