Year	Years
1970	1.06
1971	1.09
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	1.5
1983	1.54
1984	1.58
1985	1.63
1986	1.68
1987	1.73
1988	1.78
1989	1.83
1990	1.88
1991	1.94
1992	2
1993	2.06
1994	2.12
1995	2.18
1996	2.26
1997	2.33
1998	2.41
1999	2.49
2000	2.57
2001	2.65
2002	2.73
2003	2.81
2004	2.9
2005	2.98
2006	3.07
2007	3.16
2008	3.25
2009	3.34
2010	3.43
2011	3.52
2012	3.61
2013	3.7
2014	3.8
2015	3.89