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	0.37
1980	0.38
1981	0.39
1982	0.4
1983	0.42
1984	0.43
1985	0.44
1986	0.46
1987	0.47
1988	0.49
1989	0.5
1990	0.52
1991	0.53
1992	0.55
1993	0.57
1994	0.59
1995	0.61
1996	0.63
1997	0.66
1998	0.68
1999	0.7
2000	0.73
2001	0.75
2002	0.78
2003	0.8
2004	0.83
2005	0.85
2006	0.88
2007	0.91
2008	0.93
2009	0.96
2010	0.99
2011	1.02
2012	1.05
2013	1.08
2014	1.12
2015	1.15