Year	Years
1970	69.22
1971	69.49
1972	69.75
1973	70.01
1974	70.34
1975	70.72
1976	71.04
1977	71.28
1978	71.49
1979	71.7
1980	71.91
1981	72.03
1982	72.16
1983	72.29
1984	72.42
1985	72.57
1986	72.72
1987	72.89
1988	73.04
1989	73.18
1990	73.7
1991	74.1
1992	74.44
1993	74.74
1994	75.02
1995	75.26
1996	75.47
1997	75.64
1998	75.78
1999	75.95
2000	76.18
2001	76.19
2002	76.22
2003	76.32
2004	76.33
2005	76.22
2006	76.26
2007	76.22
2008	76.18
2009	76.04
2010	76.03
2011	75.89
2012	75.78
2013	75.65
2014	75.56
2015	75.52
2016	75.63