Year	Years
1970	1.65
1971	1.71
1972	1.77
1973	1.82
1974	1.89
1975	1.95
1976	2.02
1977	2.09
1978	2.16
1979	2.24
1980	2.32
1981	2.4
1982	2.49
1983	2.58
1984	2.67
1985	2.78
1986	2.88
1987	2.99
1988	3.11
1989	3.23
1990	3.36
1991	3.49
1992	3.63
1993	3.78
1994	3.93
1995	4.09
1996	4.24
1997	4.38
1998	4.52
1999	4.66
2000	4.79
2001	4.93
2002	5.07
2003	5.2
2004	5.33
2005	5.47
2006	5.6
2007	5.73
2008	5.87
2009	6
2010	6.13
2011	6.26
2012	6.4
2013	6.53
2014	6.66
2015	6.79