Year	Years
1970	0.24
1971	0.25
1972	0.25
1973	0.26
1974	0.27
1975	0.28
1976	0.29
1977	0.3
1978	0.31
1979	0.32
1980	0.33
1981	0.34
1982	0.36
1983	0.37
1984	0.38
1985	0.39
1986	0.41
1987	0.42
1988	0.44
1989	0.45
1990	0.47
1991	0.48
1992	0.5
1993	0.52
1994	0.54
1995	0.55
1996	0.57
1997	0.59
1998	0.62
1999	0.64
2000	0.66
2001	0.68
2002	0.71
2003	0.73
2004	0.76
2005	0.78
2006	0.81
2007	0.84
2008	0.86
2009	0.89
2010	0.92
2011	0.95
2012	0.99
2013	1.02
2014	1.05
2015	1.09