Year	Years
1970	0.29
1971	0.3
1972	0.31
1973	0.32
1974	0.33
1975	0.35
1976	0.36
1977	0.37
1978	0.38
1979	0.4
1980	0.41
1981	0.43
1982	0.44
1983	0.46
1984	0.48
1985	0.49
1986	0.51
1987	0.53
1988	0.55
1989	0.57
1990	0.59
1991	0.61
1992	0.64
1993	0.66
1994	0.68
1995	0.71
1996	0.74
1997	0.77
1998	0.81
1999	0.84
2000	0.87
2001	0.91
2002	0.94
2003	0.98
2004	1.02
2005	1.06
2006	1.1
2007	1.14
2008	1.18
2009	1.22
2010	1.27
2011	1.31
2012	1.36
2013	1.41
2014	1.46
2015	1.51