Year	Years
1970	0.21
1971	0.22
1972	0.22
1973	0.23
1974	0.24
1975	0.25
1976	0.26
1977	0.27
1978	0.28
1979	0.29
1980	0.3
1981	0.31
1982	0.32
1983	0.33
1984	0.34
1985	0.36
1986	0.37
1987	0.38
1988	0.4
1989	0.41
1990	0.43
1991	0.44
1992	0.46
1993	0.48
1994	0.5
1995	0.52
1996	0.54
1997	0.56
1998	0.59
1999	0.61
2000	0.64
2001	0.66
2002	0.69
2003	0.72
2004	0.75
2005	0.78
2006	0.81
2007	0.84
2008	0.87
2009	0.91
2010	0.94
2011	0.98
2012	1.01
2013	1.05
2014	1.09
2015	1.12