Year	Years
1970	0.29
1971	0.3
1972	0.32
1973	0.33
1974	0.35
1975	0.36
1976	0.38
1977	0.4
1978	0.42
1979	0.44
1980	0.46
1981	0.48
1982	0.5
1983	0.53
1984	0.56
1985	0.59
1986	0.62
1987	0.65
1988	0.69
1989	0.72
1990	0.77
1991	0.81
1992	0.86
1993	0.91
1994	0.97
1995	1.03
1996	1.09
1997	1.16
1998	1.23
1999	1.3
2000	1.37
2001	1.44
2002	1.52
2003	1.59
2004	1.66
2005	1.74
2006	1.82
2007	1.9
2008	1.98
2009	2.06
2010	2.14
2011	2.22
2012	2.3
2013	2.39
2014	2.47
2015	2.55