Year	Years
1970	0.8
1971	0.82
1972	0.85
1973	0.88
1974	0.91
1975	0.94
1976	0.97
1977	1
1978	1.03
1979	1.07
1980	1.1
1981	1.14
1982	1.18
1983	1.21
1984	1.25
1985	1.3
1986	1.34
1987	1.38
1988	1.43
1989	1.47
1990	1.52
1991	1.57
1992	1.62
1993	1.67
1994	1.73
1995	1.78
1996	1.84
1997	1.89
1998	1.95
1999	2.01
2000	2.08
2001	2.14
2002	2.21
2003	2.27
2004	2.34
2005	2.41
2006	2.49
2007	2.56
2008	2.64
2009	2.72
2010	2.8
2011	2.88
2012	2.97
2013	3.05
2014	3.14
2015	3.23