Year	Years
1970	0.38
1971	0.39
1972	0.4
1973	0.41
1974	0.42
1975	0.44
1976	0.45
1977	0.46
1978	0.47
1979	0.49
1980	0.5
1981	0.51
1982	0.53
1983	0.54
1984	0.56
1985	0.57
1986	0.59
1987	0.6
1988	0.62
1989	0.64
1990	0.65
1991	0.67
1992	0.69
1993	0.71
1994	0.73
1995	0.75
1996	0.77
1997	0.79
1998	0.81
1999	0.83
2000	0.85
2001	0.87
2002	0.9
2003	0.92
2004	0.94
2005	0.97
2006	1
2007	1.02
2008	1.05
2009	1.08
2010	1.11
2011	1.14
2012	1.17
2013	1.2
2014	1.23
2015	1.26