Year	Years
1970	0.62
1971	0.64
1972	0.66
1973	0.69
1974	0.71
1975	0.73
1976	0.76
1977	0.78
1978	0.81
1979	0.84
1980	0.87
1981	0.89
1982	0.92
1983	0.95
1984	0.99
1985	1.02
1986	1.05
1987	1.09
1988	1.13
1989	1.16
1990	1.2
1991	1.24
1992	1.28
1993	1.33
1994	1.37
1995	1.41
1996	1.46
1997	1.51
1998	1.56
1999	1.62
2000	1.67
2001	1.72
2002	1.78
2003	1.84
2004	1.9
2005	1.96
2006	2.02
2007	2.09
2008	2.15
2009	2.22
2010	2.29
2011	2.36
2012	2.43
2013	2.51
2014	2.58
2015	2.66