Year	Years
1970	0.28
1971	0.29
1972	0.3
1973	0.31
1974	0.32
1975	0.33
1976	0.34
1977	0.35
1978	0.36
1979	0.38
1980	0.39
1981	0.4
1982	0.42
1983	0.43
1984	0.45
1985	0.46
1986	0.48
1987	0.5
1988	0.51
1989	0.53
1990	0.55
1991	0.57
1992	0.59
1993	0.61
1994	0.64
1995	0.66
1996	0.69
1997	0.71
1998	0.74
1999	0.76
2000	0.79
2001	0.82
2002	0.85
2003	0.88
2004	0.91
2005	0.94
2006	0.98
2007	1.01
2008	1.05
2009	1.08
2010	1.12
2011	1.16
2012	1.2
2013	1.24
2014	1.28
2015	1.32