Year	Years
1970	1.18
1971	1.22
1972	1.26
1973	1.3
1974	1.33
1975	1.38
1976	1.42
1977	1.46
1978	1.51
1979	1.55
1980	1.6
1981	1.65
1982	1.7
1983	1.75
1984	1.8
1985	1.86
1986	1.92
1987	1.98
1988	2.04
1989	2.1
1990	2.17
1991	2.23
1992	2.31
1993	2.38
1994	2.46
1995	2.54
1996	2.62
1997	2.69
1998	2.77
1999	2.85
2000	2.93
2001	3.01
2002	3.09
2003	3.17
2004	3.25
2005	3.34
2006	3.42
2007	3.51
2008	3.6
2009	3.68
2010	3.77
2011	3.87
2012	3.96
2013	4.05
2014	4.15
2015	4.25