Year	Years
1970	0.93
1971	0.95
1972	0.98
1973	1.01
1974	1.04
1975	1.06
1976	1.09
1977	1.12
1978	1.15
1979	1.19
1980	1.22
1981	1.25
1982	1.29
1983	1.32
1984	1.36
1985	1.4
1986	1.43
1987	1.47
1988	1.51
1989	1.55
1990	1.6
1991	1.64
1992	1.69
1993	1.73
1994	1.78
1995	1.83
1996	1.87
1997	1.92
1998	1.97
1999	2.02
2000	2.07
2001	2.13
2002	2.18
2003	2.24
2004	2.29
2005	2.35
2006	2.41
2007	2.47
2008	2.53
2009	2.6
2010	2.66
2011	2.73
2012	2.79
2013	2.86
2014	2.93
2015	3