Year	Years
1970	0.68
1971	0.7
1972	0.72
1973	0.75
1974	0.77
1975	0.8
1976	0.83
1977	0.86
1978	0.89
1979	0.92
1980	0.95
1981	0.98
1982	1.01
1983	1.05
1984	1.09
1985	1.12
1986	1.16
1987	1.2
1988	1.24
1989	1.29
1990	1.33
1991	1.38
1992	1.42
1993	1.47
1994	1.53
1995	1.58
1996	1.64
1997	1.7
1998	1.76
1999	1.82
2000	1.88
2001	1.95
2002	2.01
2003	2.08
2004	2.15
2005	2.22
2006	2.3
2007	2.37
2008	2.45
2009	2.53
2010	2.61
2011	2.69
2012	2.77
2013	2.86
2014	2.95
2015	3.04