Year	Years
1970	0.21
1971	0.22
1972	0.23
1973	0.24
1974	0.25
1975	0.26
1976	0.27
1977	0.29
1978	0.3
1979	0.31
1980	0.33
1981	0.34
1982	0.36
1983	0.38
1984	0.39
1985	0.41
1986	0.43
1987	0.45
1988	0.47
1989	0.5
1990	0.52
1991	0.55
1992	0.57
1993	0.6
1994	0.63
1995	0.66
1996	0.69
1997	0.71
1998	0.74
1999	0.77
2000	0.81
2001	0.84
2002	0.87
2003	0.9
2004	0.94
2005	0.97
2006	1
2007	1.04
2008	1.07
2009	1.11
2010	1.15
2011	1.18
2012	1.22
2013	1.26
2014	1.3
2015	1.34