Year	Years
1970	1.82
1971	1.87
1972	1.93
1973	1.99
1974	2.05
1975	2.11
1976	2.17
1977	2.23
1978	2.29
1979	2.36
1980	2.43
1981	2.5
1982	2.57
1983	2.64
1984	2.72
1985	2.79
1986	2.87
1987	2.95
1988	3.03
1989	3.11
1990	3.2
1991	3.29
1992	3.37
1993	3.47
1994	3.56
1995	3.66
1996	3.76
1997	3.86
1998	3.97
1999	4.08
2000	4.19
2001	4.31
2002	4.43
2003	4.54
2004	4.67
2005	4.79
2006	4.91
2007	5.04
2008	5.17
2009	5.3
2010	5.44
2011	5.57
2012	5.71
2013	5.85
2014	5.99
2015	6.13