Year	Years
1970	0.97
1971	1
1972	1.02
1973	1.05
1974	1.08
1975	1.11
1976	1.14
1977	1.17
1978	1.2
1979	1.23
1980	1.26
1981	1.3
1982	1.33
1983	1.36
1984	1.4
1985	1.44
1986	1.47
1987	1.51
1988	1.55
1989	1.59
1990	1.63
1991	1.67
1992	1.71
1993	1.76
1994	1.8
1995	1.85
1996	1.9
1997	1.94
1998	1.99
1999	2.04
2000	2.1
2001	2.15
2002	2.2
2003	2.26
2004	2.31
2005	2.37
2006	2.43
2007	2.49
2008	2.55
2009	2.62
2010	2.68
2011	2.75
2012	2.81
2013	2.88
2014	2.95
2015	3.02