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	1.24
1980	1.27
1981	1.3
1982	1.34
1983	1.37
1984	1.41
1985	1.45
1986	1.49
1987	1.53
1988	1.57
1989	1.61
1990	1.65
1991	1.7
1992	1.74
1993	1.79
1994	1.84
1995	1.89
1996	1.94
1997	1.99
1998	2.04
1999	2.1
2000	2.15
2001	2.21
2002	2.26
2003	2.32
2004	2.38
2005	2.44
2006	2.5
2007	2.57
2008	2.63
2009	2.7
2010	2.77
2011	2.83
2012	2.9
2013	2.98
2014	3.05
2015	3.12