Year	Years
1970	1.19
1971	1.23
1972	1.27
1973	1.31
1974	1.35
1975	1.39
1976	1.44
1977	1.48
1978	1.53
1979	1.58
1980	1.63
1981	1.68
1982	1.73
1983	1.79
1984	1.84
1985	1.9
1986	1.96
1987	2.02
1988	2.08
1989	2.14
1990	2.21
1991	2.28
1992	2.35
1993	2.42
1994	2.49
1995	2.57
1996	2.64
1997	2.72
1998	2.81
1999	2.89
2000	2.98
2001	3.07
2002	3.16
2003	3.25
2004	3.35
2005	3.44
2006	3.54
2007	3.64
2008	3.75
2009	3.85
2010	3.96
2011	4.07
2012	4.19
2013	4.3
2014	4.42
2015	4.54