Year	Years
1970	1.1
1971	1.14
1972	1.17
1973	1.21
1974	1.26
1975	1.3
1976	1.34
1977	1.39
1978	1.44
1979	1.48
1980	1.53
1981	1.59
1982	1.64
1983	1.7
1984	1.75
1985	1.81
1986	1.88
1987	1.94
1988	2.01
1989	2.08
1990	2.15
1991	2.22
1992	2.3
1993	2.38
1994	2.46
1995	2.55
1996	2.63
1997	2.72
1998	2.8
1999	2.89
2000	2.98
2001	3.08
2002	3.17
2003	3.27
2004	3.37
2005	3.47
2006	3.57
2007	3.68
2008	3.79
2009	3.9
2010	4.01
2011	4.12
2012	4.24
2013	4.36
2014	4.48
2015	4.6