Year	Years
1970	1.08
1971	1.12
1972	1.16
1973	1.19
1974	1.23
1975	1.27
1976	1.31
1977	1.36
1978	1.4
1979	1.45
1980	1.49
1981	1.54
1982	1.59
1983	1.64
1984	1.69
1985	1.75
1986	1.8
1987	1.86
1988	1.92
1989	1.98
1990	2.04
1991	2.1
1992	2.17
1993	2.23
1994	2.3
1995	2.37
1996	2.45
1997	2.53
1998	2.61
1999	2.7
2000	2.78
2001	2.87
2002	2.96
2003	3.06
2004	3.15
2005	3.25
2006	3.35
2007	3.45
2008	3.55
2009	3.66
2010	3.76
2011	3.87
2012	3.98
2013	4.09
2014	4.21
2015	4.32