Year	Years
1970	1.3
1971	1.34
1972	1.4
1973	1.45
1974	1.5
1975	1.56
1976	1.62
1977	1.68
1978	1.75
1979	1.81
1980	1.88
1981	1.95
1982	2.03
1983	2.11
1984	2.19
1985	2.27
1986	2.36
1987	2.45
1988	2.55
1989	2.65
1990	2.75
1991	2.86
1992	2.97
1993	3.08
1994	3.19
1995	3.31
1996	3.42
1997	3.54
1998	3.65
1999	3.77
2000	3.88
2001	4
2002	4.12
2003	4.25
2004	4.37
2005	4.49
2006	4.62
2007	4.75
2008	4.87
2009	5
2010	5.13
2011	5.26
2012	5.39
2013	5.52
2014	5.66
2015	5.79