Year	Years
1970	1.75
1971	1.8
1972	1.85
1973	1.89
1974	1.94
1975	1.99
1976	2.04
1977	2.09
1978	2.15
1979	2.2
1980	2.26
1981	2.31
1982	2.37
1983	2.43
1984	2.49
1985	2.55
1986	2.61
1987	2.68
1988	2.74
1989	2.81
1990	2.88
1991	2.95
1992	3.02
1993	3.09
1994	3.17
1995	3.24
1996	3.32
1997	3.4
1998	3.48
1999	3.56
2000	3.64
2001	3.73
2002	3.81
2003	3.9
2004	3.99
2005	4.08
2006	4.17
2007	4.27
2008	4.36
2009	4.46
2010	4.56
2011	4.66
2012	4.76
2013	4.86
2014	4.97
2015	5.08