Year	Years
1970	0.26
1971	0.27
1972	0.28
1973	0.29
1974	0.3
1975	0.31
1976	0.32
1977	0.33
1978	0.34
1979	0.36
1980	0.37
1981	0.39
1982	0.4
1983	0.42
1984	0.43
1985	0.45
1986	0.47
1987	0.49
1988	0.51
1989	0.53
1990	0.55
1991	0.58
1992	0.6
1993	0.63
1994	0.65
1995	0.68
1996	0.71
1997	0.74
1998	0.77
1999	0.8
2000	0.83
2001	0.86
2002	0.89
2003	0.92
2004	0.96
2005	0.99
2006	1.02
2007	1.06
2008	1.1
2009	1.14
2010	1.17
2011	1.21
2012	1.26
2013	1.3
2014	1.34
2015	1.39