Year	Years
1970	0.97
1971	1
1972	1.03
1973	1.06
1974	1.09
1975	1.12
1976	1.15
1977	1.18
1978	1.22
1979	1.25
1980	1.29
1981	1.32
1982	1.36
1983	1.4
1984	1.44
1985	1.48
1986	1.52
1987	1.56
1988	1.61
1989	1.65
1990	1.7
1991	1.75
1992	1.8
1993	1.85
1994	1.9
1995	1.96
1996	2.02
1997	2.08
1998	2.14
1999	2.2
2000	2.26
2001	2.33
2002	2.39
2003	2.46
2004	2.53
2005	2.59
2006	2.66
2007	2.73
2008	2.81
2009	2.88
2010	2.95
2011	3.03
2012	3.1
2013	3.18
2014	3.26
2015	3.34