Year	Years
1970	1.14
1971	1.18
1972	1.23
1973	1.27
1974	1.32
1975	1.37
1976	1.42
1977	1.47
1978	1.53
1979	1.59
1980	1.65
1981	1.72
1982	1.78
1983	1.85
1984	1.93
1985	2.01
1986	2.09
1987	2.18
1988	2.27
1989	2.37
1990	2.48
1991	2.59
1992	2.71
1993	2.85
1994	2.99
1995	3.14
1996	3.3
1997	3.46
1998	3.62
1999	3.78
2000	3.95
2001	4.11
2002	4.27
2003	4.43
2004	4.59
2005	4.76
2006	4.92
2007	5.09
2008	5.25
2009	5.42
2010	5.58
2011	5.75
2012	5.92
2013	6.09
2014	6.26
2015	6.43