Year	Years
1970	0.91
1971	0.94
1972	0.96
1973	0.99
1974	1.01
1975	1.04
1976	1.07
1977	1.1
1978	1.13
1979	1.16
1980	1.19
1981	1.22
1982	1.26
1983	1.29
1984	1.32
1985	1.36
1986	1.4
1987	1.43
1988	1.47
1989	1.51
1990	1.55
1991	1.59
1992	1.63
1993	1.68
1994	1.72
1995	1.77
1996	1.82
1997	1.86
1998	1.91
1999	1.96
2000	2.01
2001	2.07
2002	2.12
2003	2.18
2004	2.23
2005	2.29
2006	2.35
2007	2.41
2008	2.47
2009	2.53
2010	2.59
2011	2.66
2012	2.72
2013	2.79
2014	2.86
2015	2.93