Year	Years
1970	1.15
1971	1.19
1972	1.23
1973	1.27
1974	1.31
1975	1.36
1976	1.41
1977	1.45
1978	1.5
1979	1.56
1980	1.61
1981	1.67
1982	1.73
1983	1.79
1984	1.85
1985	1.92
1986	1.98
1987	2.05
1988	2.13
1989	2.2
1990	2.28
1991	2.36
1992	2.44
1993	2.52
1994	2.6
1995	2.68
1996	2.75
1997	2.82
1998	2.89
1999	2.96
2000	3.03
2001	3.1
2002	3.17
2003	3.25
2004	3.32
2005	3.4
2006	3.48
2007	3.56
2008	3.64
2009	3.72
2010	3.81
2011	3.89
2012	3.98
2013	4.07
2014	4.16
2015	4.25