Year	Years
1970	1.21
1971	1.24
1972	1.28
1973	1.31
1974	1.35
1975	1.39
1976	1.43
1977	1.47
1978	1.52
1979	1.56
1980	1.61
1981	1.65
1982	1.7
1983	1.75
1984	1.8
1985	1.85
1986	1.91
1987	1.97
1988	2.02
1989	2.08
1990	2.15
1991	2.21
1992	2.28
1993	2.34
1994	2.41
1995	2.49
1996	2.55
1997	2.62
1998	2.7
1999	2.77
2000	2.84
2001	2.91
2002	2.99
2003	3.07
2004	3.14
2005	3.22
2006	3.3
2007	3.38
2008	3.47
2009	3.55
2010	3.64
2011	3.72
2012	3.81
2013	3.9
2014	3.99
2015	4.09