Year	Years
1970	1.16
1971	1.2
1972	1.23
1973	1.26
1974	1.29
1975	1.33
1976	1.36
1977	1.4
1978	1.44
1979	1.48
1980	1.51
1981	1.55
1982	1.6
1983	1.64
1984	1.68
1985	1.72
1986	1.77
1987	1.82
1988	1.86
1989	1.91
1990	1.96
1991	2.01
1992	2.06
1993	2.12
1994	2.17
1995	2.23
1996	2.29
1997	2.34
1998	2.4
1999	2.47
2000	2.53
2001	2.59
2002	2.66
2003	2.72
2004	2.79
2005	2.86
2006	2.93
2007	3
2008	3.08
2009	3.15
2010	3.23
2011	3.3
2012	3.38
2013	3.46
2014	3.55
2015	3.63