Year	Years
1970	1.35
1971	1.38
1972	1.42
1973	1.46
1974	1.49
1975	1.53
1976	1.57
1977	1.61
1978	1.66
1979	1.7
1980	1.74
1981	1.79
1982	1.83
1983	1.88
1984	1.93
1985	1.97
1986	2.02
1987	2.08
1988	2.13
1989	2.18
1990	2.23
1991	2.29
1992	2.35
1993	2.4
1994	2.46
1995	2.52
1996	2.58
1997	2.65
1998	2.71
1999	2.78
2000	2.84
2001	2.91
2002	2.98
2003	3.05
2004	3.13
2005	3.2
2006	3.28
2007	3.35
2008	3.43
2009	3.51
2010	3.6
2011	3.68
2012	3.76
2013	3.85
2014	3.94
2015	4.03