Year	Years
1970	60.78
1971	61.1
1972	61.39
1973	61.85
1974	62.34
1975	62.73
1976	63.08
1977	63.42
1978	63.75
1979	64.05
1980	64.23
1981	64.38
1982	64.43
1983	64.54
1984	64.64
1985	64.69
1986	64.86
1987	65.07
1988	65
1989	64.91
1990	64.73
1991	64.71
1992	64.65
1993	64.61
1994	64.64
1995	64.5
1996	64.37
1997	64.11
1998	63.93
1999	63.72
2000	63.31
2001	63.42
2002	63.34
2003	63.28
2004	63.21
2005	63.14
2006	63.05
2007	63.22
2008	63.37
2009	63.54
2010	63.72
2011	63.91
2012	64.1
2013	64.29
2014	64.46
2015	64.67
2016	65