Year	Years
1970	0.23
1971	0.24
1972	0.25
1973	0.26
1974	0.27
1975	0.28
1976	0.29
1977	0.3
1978	0.31
1979	0.32
1980	0.33
1981	0.34
1982	0.35
1983	0.36
1984	0.37
1985	0.39
1986	0.4
1987	0.41
1988	0.43
1989	0.44
1990	0.46
1991	0.47
1992	0.49
1993	0.51
1994	0.52
1995	0.54
1996	0.56
1997	0.58
1998	0.6
1999	0.62
2000	0.64
2001	0.66
2002	0.68
2003	0.71
2004	0.73
2005	0.76
2006	0.78
2007	0.81
2008	0.83
2009	0.86
2010	0.89
2011	0.92
2012	0.95
2013	0.98
2014	1.02
2015	1.05