Year	Percent
1970	69.9262
1971	70.75812
1972	71.73145
1973	72.53886
1974	73.43486
1975	74.33775
1976	75.20259
1977	76.06973
1978	77.01863
1979	77.96353
1980	78.86905
1981	79.85401
1982	80.97282
1983	81.79272
1984	82.96703
1985	84.09704
1986	85.07266
1987	86.1399
1988	87.27735
1989	88.26467
1990	89.33824
1991	90.49338
1992	91.48936
1993	92.56678
1994	93.49315
1995	94.50056
1996	95.02762
1997	95.54348
1998	96.14561
1999	96.62447
2000	97.19335
2001	97.5435
2002	97.98184
2003	98.40796
2004	98.82237
2005	99.12875
2006	99.52245
2007	99.8115
2008	100.18605
2009	100.45914
2010	100.72529
2011	100.98566
2012	101.23894
2013	101.48731
2014	101.72861
2015	101.96581