Year	Years
1970	1.15
1971	1.19
1972	1.23
1973	1.27
1974	1.31
1975	1.35
1976	1.39
1977	1.44
1978	1.48
1979	1.53
1980	1.58
1981	1.63
1982	1.68
1983	1.73
1984	1.78
1985	1.84
1986	1.9
1987	1.96
1988	2.02
1989	2.08
1990	2.14
1991	2.21
1992	2.27
1993	2.34
1994	2.41
1995	2.49
1996	2.56
1997	2.64
1998	2.71
1999	2.79
2000	2.87
2001	2.96
2002	3.04
2003	3.13
2004	3.22
2005	3.31
2006	3.41
2007	3.5
2008	3.6
2009	3.7
2010	3.81
2011	3.91
2012	4.02
2013	4.13
2014	4.24
2015	4.35