Year	Years
1970	0.65
1971	0.67
1972	0.69
1973	0.71
1974	0.74
1975	0.76
1976	0.79
1977	0.81
1978	0.84
1979	0.87
1980	0.9
1981	0.93
1982	0.97
1983	1
1984	1.04
1985	1.08
1986	1.12
1987	1.16
1988	1.2
1989	1.25
1990	1.3
1991	1.35
1992	1.41
1993	1.46
1994	1.52
1995	1.59
1996	1.65
1997	1.71
1998	1.77
1999	1.83
2000	1.89
2001	1.95
2002	2.01
2003	2.07
2004	2.14
2005	2.2
2006	2.26
2007	2.33
2008	2.39
2009	2.46
2010	2.53
2011	2.6
2012	2.67
2013	2.74
2014	2.81
2015	2.88