Year	Percent
1970	86.86327
1971	87.23684
1972	87.71022
1973	88.16794
1974	88.625
1975	89.05289
1976	89.48005
1977	89.77408
1978	90.28103
1979	90.6682
1980	91.14642
1981	91.39665
1982	91.85022
1983	92.29099
1984	92.62032
1985	92.93249
1986	93.34027
1987	93.73717
1988	94.02229
1989	94.39439
1990	94.66403
1991	95.01953
1992	95.3668
1993	95.70611
1994	95.9434
1995	96.35854
1996	96.58041
1997	96.80073
1998	97.10407
1999	97.40143
2000	97.69299
2001	97.97891
2002	98.17391
2003	98.44961
2004	98.63598
2005	98.90203
2006	99.08027
2007	99.42005
2008	99.58983
2009	99.83753
2010	100
2011	100.23904
2012	100.47393
2013	100.70423
2014	100.85271
2015	101.07527