Year	Years
1970	0.28
1971	0.29
1972	0.3
1973	0.31
1974	0.32
1975	0.33
1976	0.34
1977	0.35
1978	0.36
1979	0.38
1980	0.39
1981	0.4
1982	0.42
1983	0.43
1984	0.44
1985	0.46
1986	0.47
1987	0.49
1988	0.51
1989	0.52
1990	0.54
1991	0.56
1992	0.58
1993	0.59
1994	0.61
1995	0.63
1996	0.66
1997	0.68
1998	0.7
1999	0.73
2000	0.75
2001	0.78
2002	0.81
2003	0.83
2004	0.86
2005	0.89
2006	0.92
2007	0.95
2008	0.98
2009	1.02
2010	1.05
2011	1.08
2012	1.12
2013	1.16
2014	1.2
2015	1.23