Year	Years
1970	0.27
1971	0.28
1972	0.29
1973	0.3
1974	0.31
1975	0.32
1976	0.33
1977	0.34
1978	0.35
1979	0.36
1980	0.38
1981	0.39
1982	0.4
1983	0.42
1984	0.43
1985	0.45
1986	0.46
1987	0.48
1988	0.5
1989	0.52
1990	0.53
1991	0.55
1992	0.57
1993	0.6
1994	0.62
1995	0.64
1996	0.66
1997	0.69
1998	0.71
1999	0.74
2000	0.77
2001	0.8
2002	0.82
2003	0.85
2004	0.88
2005	0.91
2006	0.94
2007	0.98
2008	1.01
2009	1.04
2010	1.08
2011	1.12
2012	1.15
2013	1.19
2014	1.23
2015	1.27