Year	Years
1970	0.22
1971	0.23
1972	0.24
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	0.37
1986	0.38
1987	0.39
1988	0.41
1989	0.43
1990	0.44
1991	0.46
1992	0.48
1993	0.5
1994	0.53
1995	0.55
1996	0.57
1997	0.59
1998	0.61
1999	0.63
2000	0.65
2001	0.67
2002	0.7
2003	0.72
2004	0.74
2005	0.77
2006	0.79
2007	0.81
2008	0.84
2009	0.87
2010	0.89
2011	0.92
2012	0.95
2013	0.97
2014	1
2015	1.03