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	0.41
1984	0.42
1985	0.44
1986	0.45
1987	0.46
1988	0.47
1989	0.49
1990	0.5
1991	0.52
1992	0.53
1993	0.55
1994	0.57
1995	0.58
1996	0.6
1997	0.62
1998	0.64
1999	0.66
2000	0.68
2001	0.71
2002	0.73
2003	0.75
2004	0.77
2005	0.8
2006	0.82
2007	0.84
2008	0.87
2009	0.9
2010	0.92
2011	0.95
2012	0.98
2013	1
2014	1.03
2015	1.06