Year	Years
1970	0.81
1971	0.84
1972	0.87
1973	0.9
1974	0.94
1975	0.97
1976	1.01
1977	1.05
1978	1.09
1979	1.13
1980	1.18
1981	1.22
1982	1.27
1983	1.32
1984	1.38
1985	1.43
1986	1.49
1987	1.55
1988	1.62
1989	1.68
1990	1.75
1991	1.82
1992	1.9
1993	1.98
1994	2.06
1995	2.15
1996	2.24
1997	2.34
1998	2.43
1999	2.53
2000	2.63
2001	2.73
2002	2.84
2003	2.94
2004	3.05
2005	3.16
2006	3.27
2007	3.38
2008	3.49
2009	3.6
2010	3.71
2011	3.82
2012	3.93
2013	4.04
2014	4.15
2015	4.26