Year	Years
1970	1.15
1971	1.18
1972	1.21
1973	1.24
1974	1.28
1975	1.31
1976	1.35
1977	1.39
1978	1.42
1979	1.46
1980	1.5
1981	1.54
1982	1.59
1983	1.63
1984	1.67
1985	1.72
1986	1.77
1987	1.82
1988	1.86
1989	1.92
1990	1.97
1991	2.02
1992	2.08
1993	2.13
1994	2.19
1995	2.25
1996	2.31
1997	2.38
1998	2.44
1999	2.51
2000	2.58
2001	2.65
2002	2.72
2003	2.79
2004	2.87
2005	2.94
2006	3.02
2007	3.1
2008	3.18
2009	3.26
2010	3.34
2011	3.42
2012	3.51
2013	3.59
2014	3.68
2015	3.76