Year	Years
1970	0.7
1971	0.72
1972	0.74
1973	0.76
1974	0.79
1975	0.81
1976	0.83
1977	0.86
1978	0.88
1979	0.91
1980	0.94
1981	0.97
1982	0.99
1983	1.02
1984	1.05
1985	1.09
1986	1.12
1987	1.15
1988	1.19
1989	1.22
1990	1.26
1991	1.3
1992	1.34
1993	1.38
1994	1.42
1995	1.46
1996	1.51
1997	1.56
1998	1.61
1999	1.66
2000	1.71
2001	1.76
2002	1.81
2003	1.86
2004	1.91
2005	1.97
2006	2.02
2007	2.08
2008	2.13
2009	2.19
2010	2.25
2011	2.31
2012	2.37
2013	2.43
2014	2.49
2015	2.55