Year	Years
1970	0.94
1971	0.97
1972	1
1973	1.03
1974	1.06
1975	1.09
1976	1.13
1977	1.16
1978	1.2
1979	1.23
1980	1.27
1981	1.31
1982	1.35
1983	1.39
1984	1.43
1985	1.48
1986	1.52
1987	1.57
1988	1.62
1989	1.67
1990	1.73
1991	1.78
1992	1.84
1993	1.9
1994	1.96
1995	2.02
1996	2.09
1997	2.16
1998	2.23
1999	2.3
2000	2.37
2001	2.44
2002	2.51
2003	2.59
2004	2.66
2005	2.74
2006	2.81
2007	2.89
2008	2.97
2009	3.05
2010	3.12
2011	3.2
2012	3.28
2013	3.36
2014	3.44
2015	3.52