Year	Years
1970	0.78
1971	0.8
1972	0.82
1973	0.85
1974	0.87
1975	0.9
1976	0.92
1977	0.95
1978	0.97
1979	1
1980	1.03
1981	1.06
1982	1.09
1983	1.12
1984	1.16
1985	1.19
1986	1.22
1987	1.26
1988	1.29
1989	1.33
1990	1.37
1991	1.41
1992	1.45
1993	1.49
1994	1.53
1995	1.57
1996	1.62
1997	1.66
1998	1.71
1999	1.75
2000	1.8
2001	1.85
2002	1.9
2003	1.95
2004	2
2005	2.05
2006	2.11
2007	2.16
2008	2.22
2009	2.27
2010	2.33
2011	2.39
2012	2.45
2013	2.51
2014	2.58
2015	2.64