Year	Years
1970	0.31
1971	0.32
1972	0.33
1973	0.34
1974	0.35
1975	0.36
1976	0.38
1977	0.39
1978	0.4
1979	0.42
1980	0.43
1981	0.44
1982	0.46
1983	0.48
1984	0.49
1985	0.51
1986	0.53
1987	0.55
1988	0.57
1989	0.58
1990	0.61
1991	0.63
1992	0.65
1993	0.67
1994	0.7
1995	0.72
1996	0.75
1997	0.78
1998	0.81
1999	0.84
2000	0.87
2001	0.9
2002	0.93
2003	0.97
2004	1
2005	1.04
2006	1.07
2007	1.11
2008	1.15
2009	1.19
2010	1.23
2011	1.27
2012	1.32
2013	1.36
2014	1.41
2015	1.45