Year	Years
1970	0.82
1971	0.84
1972	0.87
1973	0.9
1974	0.93
1975	0.96
1976	0.99
1977	1.02
1978	1.05
1979	1.08
1980	1.12
1981	1.15
1982	1.19
1983	1.22
1984	1.26
1985	1.3
1986	1.34
1987	1.38
1988	1.42
1989	1.46
1990	1.51
1991	1.55
1992	1.6
1993	1.64
1994	1.69
1995	1.73
1996	1.78
1997	1.84
1998	1.89
1999	1.94
2000	2
2001	2.06
2002	2.12
2003	2.18
2004	2.24
2005	2.31
2006	2.38
2007	2.45
2008	2.52
2009	2.59
2010	2.67
2011	2.74
2012	2.82
2013	2.91
2014	2.99
2015	3.08