Year	Years
1970	0.98
1971	1.02
1972	1.06
1973	1.1
1974	1.15
1975	1.19
1976	1.24
1977	1.29
1978	1.34
1979	1.4
1980	1.45
1981	1.51
1982	1.58
1983	1.64
1984	1.71
1985	1.78
1986	1.86
1987	1.94
1988	2.02
1989	2.11
1990	2.2
1991	2.29
1992	2.39
1993	2.5
1994	2.61
1995	2.72
1996	2.85
1997	2.98
1998	3.11
1999	3.24
2000	3.38
2001	3.52
2002	3.66
2003	3.8
2004	3.94
2005	4.09
2006	4.24
2007	4.38
2008	4.53
2009	4.68
2010	4.83
2011	4.97
2012	5.12
2013	5.26
2014	5.41
2015	5.55