Year	Years
1970	0.59
1971	0.61
1972	0.63
1973	0.65
1974	0.68
1975	0.7
1976	0.72
1977	0.75
1978	0.77
1979	0.8
1980	0.83
1981	0.86
1982	0.89
1983	0.92
1984	0.96
1985	1
1986	1.03
1987	1.08
1988	1.12
1989	1.16
1990	1.21
1991	1.27
1992	1.32
1993	1.38
1994	1.44
1995	1.51
1996	1.57
1997	1.63
1998	1.69
1999	1.75
2000	1.82
2001	1.88
2002	1.94
2003	2.01
2004	2.07
2005	2.14
2006	2.21
2007	2.27
2008	2.34
2009	2.41
2010	2.48
2011	2.55
2012	2.62
2013	2.7
2014	2.77
2015	2.85