Year	Years
1970	0.28
1971	0.29
1972	0.3
1973	0.3
1974	0.31
1975	0.32
1976	0.33
1977	0.34
1978	0.35
1979	0.36
1980	0.37
1981	0.38
1982	0.39
1983	0.4
1984	0.41
1985	0.42
1986	0.44
1987	0.45
1988	0.46
1989	0.47
1990	0.49
1991	0.5
1992	0.51
1993	0.53
1994	0.54
1995	0.56
1996	0.57
1997	0.59
1998	0.6
1999	0.62
2000	0.64
2001	0.66
2002	0.67
2003	0.69
2004	0.71
2005	0.73
2006	0.75
2007	0.77
2008	0.79
2009	0.81
2010	0.84
2011	0.86
2012	0.88
2013	0.91
2014	0.93
2015	0.96