Year	Years
1970	0.52
1971	0.54
1972	0.56
1973	0.59
1974	0.61
1975	0.63
1976	0.66
1977	0.69
1978	0.72
1979	0.75
1980	0.78
1981	0.81
1982	0.85
1983	0.88
1984	0.92
1985	0.96
1986	1
1987	1.05
1988	1.09
1989	1.14
1990	1.19
1991	1.25
1992	1.31
1993	1.37
1994	1.43
1995	1.49
1996	1.56
1997	1.63
1998	1.7
1999	1.77
2000	1.85
2001	1.92
2002	2
2003	2.08
2004	2.16
2005	2.24
2006	2.32
2007	2.4
2008	2.49
2009	2.57
2010	2.66
2011	2.74
2012	2.83
2013	2.91
2014	3
2015	3.09