Year	Years
1970	0.8
1971	0.83
1972	0.86
1973	0.88
1974	0.91
1975	0.94
1976	0.97
1977	1
1978	1.04
1979	1.07
1980	1.1
1981	1.14
1982	1.17
1983	1.21
1984	1.25
1985	1.29
1986	1.33
1987	1.37
1988	1.41
1989	1.45
1990	1.5
1991	1.55
1992	1.59
1993	1.64
1994	1.69
1995	1.74
1996	1.8
1997	1.85
1998	1.91
1999	1.97
2000	2.03
2001	2.09
2002	2.15
2003	2.22
2004	2.28
2005	2.35
2006	2.42
2007	2.49
2008	2.57
2009	2.65
2010	2.72
2011	2.8
2012	2.89
2013	2.97
2014	3.06
2015	3.15