Year	Years
1970	0.3
1971	0.31
1972	0.32
1973	0.33
1974	0.34
1975	0.35
1976	0.36
1977	0.38
1978	0.39
1979	0.4
1980	0.42
1981	0.43
1982	0.45
1983	0.46
1984	0.48
1985	0.49
1986	0.51
1987	0.53
1988	0.54
1989	0.56
1990	0.58
1991	0.6
1992	0.62
1993	0.64
1994	0.66
1995	0.68
1996	0.71
1997	0.73
1998	0.76
1999	0.78
2000	0.81
2001	0.83
2002	0.86
2003	0.89
2004	0.92
2005	0.95
2006	0.98
2007	1.01
2008	1.05
2009	1.08
2010	1.12
2011	1.15
2012	1.19
2013	1.23
2014	1.27
2015	1.31