Year	Percent
1970	87.37705
1971	87.94212
1972	88.32808
1973	88.85449
1974	89.20973
1975	89.70149
1976	90.19034
1977	90.64748
1978	90.96045
1979	91.40083
1980	91.95089
1981	92.35925
1982	92.75362
1983	93.13472
1984	93.50318
1985	93.98496
1986	94.21182
1987	94.66667
1988	94.98807
1989	95.41716
1990	95.72254
1991	96.12756
1992	96.52076
1993	96.90265
1994	97.05882
1995	97.42213
1996	97.77542
1997	98.11912
1998	98.45361
1999	98.67886
2000	98.99699
2001	99.30693
2002	99.51124
2003	99.7107
2004	100
2005	100.28222
2006	100.46425
2007	100.73394
2008	100.99728
2009	101.25448
2010	101.41593
2011	101.66229
2012	101.90311
2013	102.05128
2014	102.28233
2015	102.50836