Year	Years
1970	0.32
1971	0.34
1972	0.35
1973	0.36
1974	0.37
1975	0.38
1976	0.4
1977	0.41
1978	0.42
1979	0.44
1980	0.45
1981	0.47
1982	0.48
1983	0.5
1984	0.52
1985	0.54
1986	0.55
1987	0.57
1988	0.59
1989	0.61
1990	0.63
1991	0.65
1992	0.68
1993	0.7
1994	0.72
1995	0.75
1996	0.77
1997	0.8
1998	0.82
1999	0.85
2000	0.88
2001	0.91
2002	0.94
2003	0.97
2004	1
2005	1.03
2006	1.06
2007	1.1
2008	1.13
2009	1.17
2010	1.21
2011	1.25
2012	1.29
2013	1.33
2014	1.37
2015	1.41