Year	Years
1970	1.75
1971	1.8
1972	1.87
1973	1.93
1974	1.99
1975	2.06
1976	2.13
1977	2.21
1978	2.28
1979	2.36
1980	2.44
1981	2.52
1982	2.61
1983	2.7
1984	2.79
1985	2.89
1986	2.99
1987	3.09
1988	3.2
1989	3.31
1990	3.43
1991	3.55
1992	3.67
1993	3.79
1994	3.93
1995	4.06
1996	4.2
1997	4.33
1998	4.47
1999	4.61
2000	4.76
2001	4.9
2002	5.05
2003	5.19
2004	5.34
2005	5.49
2006	5.64
2007	5.79
2008	5.94
2009	6.1
2010	6.25
2011	6.4
2012	6.55
2013	6.71
2014	6.86
2015	7.02