Year	Years
1970	1.6
1971	1.66
1972	1.71
1973	1.77
1974	1.83
1975	1.89
1976	1.95
1977	2.01
1978	2.08
1979	2.14
1980	2.21
1981	2.29
1982	2.36
1983	2.44
1984	2.52
1985	2.6
1986	2.68
1987	2.77
1988	2.86
1989	2.95
1990	3.05
1991	3.14
1992	3.24
1993	3.35
1994	3.46
1995	3.57
1996	3.68
1997	3.8
1998	3.92
1999	4.04
2000	4.17
2001	4.29
2002	4.42
2003	4.55
2004	4.68
2005	4.81
2006	4.95
2007	5.08
2008	5.22
2009	5.35
2010	5.49
2011	5.63
2012	5.77
2013	5.91
2014	6.05
2015	6.2