Year	Years
1970	0.22
1971	0.23
1972	0.23
1973	0.24
1974	0.25
1975	0.26
1976	0.27
1977	0.28
1978	0.29
1979	0.3
1980	0.31
1981	0.32
1982	0.33
1983	0.34
1984	0.35
1985	0.36
1986	0.38
1987	0.39
1988	0.4
1989	0.42
1990	0.43
1991	0.44
1992	0.46
1993	0.48
1994	0.49
1995	0.51
1996	0.53
1997	0.55
1998	0.56
1999	0.58
2000	0.6
2001	0.62
2002	0.65
2003	0.67
2004	0.69
2005	0.71
2006	0.74
2007	0.76
2008	0.79
2009	0.81
2010	0.84
2011	0.87
2012	0.9
2013	0.93
2014	0.96
2015	0.99