Year	Years
1970	0.96
1971	0.98
1972	1.01
1973	1.04
1974	1.07
1975	1.1
1976	1.13
1977	1.16
1978	1.2
1979	1.23
1980	1.26
1981	1.3
1982	1.34
1983	1.38
1984	1.41
1985	1.45
1986	1.5
1987	1.54
1988	1.58
1989	1.63
1990	1.68
1991	1.72
1992	1.77
1993	1.82
1994	1.88
1995	1.93
1996	1.99
1997	2.05
1998	2.11
1999	2.17
2000	2.24
2001	2.3
2002	2.37
2003	2.43
2004	2.5
2005	2.56
2006	2.63
2007	2.7
2008	2.77
2009	2.84
2010	2.91
2011	2.99
2012	3.06
2013	3.14
2014	3.22
2015	3.29