Year	Years
1970	75.95
1971	76.26
1972	76.58
1973	76.9
1974	77.18
1975	77.43
1976	77.71
1977	78.01
1978	78.31
1979	78.57
1980	78.73
1981	78.8
1982	78.77
1983	78.81
1984	78.95
1985	79.07
1986	79.16
1987	79.25
1988	79.32
1989	79.4
1990	79.49
1991	79.54
1992	79.6
1993	79.8
1994	79.97
1995	80.31
1996	80.64
1997	80.97
1998	81.26
1999	81.54
2000	81.8
2001	82.05
2002	82.3
2003	82.39
2004	82.33
2005	82.45
2006	82.55
2007	82.65
2008	82.68
2009	82.65
2010	82.66
2011	82.61
2012	82.58
2013	82.58
2014	82.56
2015	82.55
2016	82.55