Year	Years
1970	0.62
1971	0.65
1972	0.67
1973	0.7
1974	0.73
1975	0.76
1976	0.79
1977	0.82
1978	0.86
1979	0.9
1980	0.93
1981	0.97
1982	1.01
1983	1.06
1984	1.11
1985	1.15
1986	1.2
1987	1.26
1988	1.32
1989	1.37
1990	1.44
1991	1.5
1992	1.57
1993	1.65
1994	1.72
1995	1.8
1996	1.88
1997	1.96
1998	2.04
1999	2.12
2000	2.2
2001	2.29
2002	2.37
2003	2.46
2004	2.55
2005	2.63
2006	2.72
2007	2.82
2008	2.91
2009	3
2010	3.1
2011	3.2
2012	3.3
2013	3.39
2014	3.5
2015	3.6