Year	Years
1970	1.17
1971	1.2
1972	1.24
1973	1.28
1974	1.32
1975	1.36
1976	1.41
1977	1.45
1978	1.49
1979	1.54
1980	1.59
1981	1.64
1982	1.69
1983	1.74
1984	1.79
1985	1.85
1986	1.91
1987	1.96
1988	2.02
1989	2.08
1990	2.15
1991	2.21
1992	2.28
1993	2.34
1994	2.41
1995	2.48
1996	2.56
1997	2.63
1998	2.71
1999	2.79
2000	2.88
2001	2.96
2002	3.05
2003	3.13
2004	3.22
2005	3.32
2006	3.41
2007	3.51
2008	3.61
2009	3.71
2010	3.81
2011	3.92
2012	4.03
2013	4.14
2014	4.25
2015	4.36