Year	Years
1970	0.83
1971	0.85
1972	0.87
1973	0.9
1974	0.93
1975	0.95
1976	0.98
1977	1.01
1978	1.04
1979	1.07
1980	1.1
1981	1.14
1982	1.17
1983	1.2
1984	1.24
1985	1.28
1986	1.32
1987	1.36
1988	1.4
1989	1.44
1990	1.49
1991	1.53
1992	1.58
1993	1.63
1994	1.68
1995	1.73
1996	1.79
1997	1.85
1998	1.91
1999	1.97
2000	2.03
2001	2.09
2002	2.15
2003	2.21
2004	2.28
2005	2.34
2006	2.41
2007	2.47
2008	2.54
2009	2.61
2010	2.68
2011	2.75
2012	2.82
2013	2.89
2014	2.97
2015	3.04