Year	Years
1970	0.25
1971	0.26
1972	0.27
1973	0.28
1974	0.29
1975	0.3
1976	0.31
1977	0.32
1978	0.33
1979	0.34
1980	0.36
1981	0.37
1982	0.38
1983	0.4
1984	0.41
1985	0.43
1986	0.44
1987	0.46
1988	0.48
1989	0.49
1990	0.51
1991	0.53
1992	0.55
1993	0.57
1994	0.59
1995	0.62
1996	0.64
1997	0.67
1998	0.7
1999	0.72
2000	0.75
2001	0.78
2002	0.81
2003	0.84
2004	0.87
2005	0.9
2006	0.93
2007	0.97
2008	1
2009	1.04
2010	1.07
2011	1.11
2012	1.15
2013	1.19
2014	1.23
2015	1.27