Year	Years
1970	1.07
1971	1.1
1972	1.13
1973	1.16
1974	1.19
1975	1.23
1976	1.26
1977	1.3
1978	1.33
1979	1.37
1980	1.41
1981	1.45
1982	1.49
1983	1.53
1984	1.58
1985	1.62
1986	1.66
1987	1.71
1988	1.76
1989	1.8
1990	1.85
1991	1.9
1992	1.95
1993	2
1994	2.05
1995	2.1
1996	2.15
1997	2.2
1998	2.25
1999	2.3
2000	2.35
2001	2.41
2002	2.46
2003	2.52
2004	2.58
2005	2.64
2006	2.7
2007	2.76
2008	2.82
2009	2.88
2010	2.94
2011	3.01
2012	3.08
2013	3.14
2014	3.21
2015	3.28