Year	Years
1970	0.98
1971	1.02
1972	1.06
1973	1.11
1974	1.15
1975	1.2
1976	1.25
1977	1.3
1978	1.36
1979	1.41
1980	1.47
1981	1.54
1982	1.6
1983	1.67
1984	1.75
1985	1.82
1986	1.91
1987	1.99
1988	2.08
1989	2.17
1990	2.27
1991	2.37
1992	2.48
1993	2.59
1994	2.71
1995	2.83
1996	2.95
1997	3.07
1998	3.19
1999	3.32
2000	3.44
2001	3.57
2002	3.69
2003	3.82
2004	3.95
2005	4.08
2006	4.21
2007	4.34
2008	4.47
2009	4.6
2010	4.72
2011	4.85
2012	4.98
2013	5.11
2014	5.23
2015	5.36