Year	Years
1970	0.45
1971	0.46
1972	0.48
1973	0.49
1974	0.5
1975	0.52
1976	0.53
1977	0.55
1978	0.56
1979	0.58
1980	0.6
1981	0.61
1982	0.63
1983	0.65
1984	0.66
1985	0.68
1986	0.7
1987	0.71
1988	0.73
1989	0.75
1990	0.77
1991	0.78
1992	0.8
1993	0.82
1994	0.83
1995	0.85
1996	0.87
1997	0.89
1998	0.91
1999	0.93
2000	0.95
2001	0.98
2002	1
2003	1.03
2004	1.06
2005	1.09
2006	1.12
2007	1.15
2008	1.18
2009	1.22
2010	1.25
2011	1.29
2012	1.33
2013	1.36
2014	1.4
2015	1.45