Year	Years
1970	1.09
1971	1.13
1972	1.17
1973	1.22
1974	1.27
1975	1.31
1976	1.36
1977	1.42
1978	1.47
1979	1.53
1980	1.58
1981	1.65
1982	1.71
1983	1.78
1984	1.85
1985	1.92
1986	1.99
1987	2.07
1988	2.15
1989	2.24
1990	2.33
1991	2.42
1992	2.51
1993	2.61
1994	2.71
1995	2.81
1996	2.9
1997	2.99
1998	3.09
1999	3.18
2000	3.28
2001	3.38
2002	3.48
2003	3.58
2004	3.68
2005	3.79
2006	3.9
2007	4.01
2008	4.12
2009	4.23
2010	4.35
2011	4.47
2012	4.59
2013	4.71
2014	4.84
2015	4.96