Year	Years
1970	0.33
1971	0.34
1972	0.35
1973	0.36
1974	0.37
1975	0.38
1976	0.39
1977	0.4
1978	0.41
1979	0.42
1980	0.43
1981	0.45
1982	0.46
1983	0.47
1984	0.49
1985	0.5
1986	0.52
1987	0.53
1988	0.55
1989	0.56
1990	0.58
1991	0.6
1992	0.62
1993	0.64
1994	0.65
1995	0.67
1996	0.7
1997	0.72
1998	0.74
1999	0.76
2000	0.78
2001	0.81
2002	0.83
2003	0.86
2004	0.88
2005	0.91
2006	0.93
2007	0.96
2008	0.99
2009	1.02
2010	1.04
2011	1.07
2012	1.1
2013	1.13
2014	1.17
2015	1.2