Year	Years
1970	0.99
1971	1
1972	1.02
1973	1.03
1974	1.04
1975	1.06
1976	1.07
1977	1.08
1978	1.09
1979	1.1
1980	1.11
1981	1.12
1982	1.13
1983	1.13
1984	1.14
1985	1.14
1986	1.15
1987	1.15
1988	1.15
1989	1.15
1990	1.16
1991	1.16
1992	1.16
1993	1.16
1994	1.16
1995	1.16
1996	1.18
1997	1.2
1998	1.23
1999	1.25
2000	1.28
2001	1.31
2002	1.34
2003	1.37
2004	1.4
2005	1.43
2006	1.46
2007	1.5
2008	1.53
2009	1.57
2010	1.61
2011	1.65
2012	1.69
2013	1.73
2014	1.77
2015	1.81