Year	Years
1970	1.2
1971	1.24
1972	1.28
1973	1.32
1974	1.37
1975	1.41
1976	1.46
1977	1.5
1978	1.55
1979	1.6
1980	1.65
1981	1.71
1982	1.76
1983	1.82
1984	1.87
1985	1.93
1986	1.99
1987	2.05
1988	2.12
1989	2.18
1990	2.25
1991	2.32
1992	2.38
1993	2.45
1994	2.53
1995	2.6
1996	2.67
1997	2.75
1998	2.83
1999	2.91
2000	2.99
2001	3.08
2002	3.16
2003	3.25
2004	3.34
2005	3.43
2006	3.52
2007	3.62
2008	3.71
2009	3.81
2010	3.91
2011	4.01
2012	4.12
2013	4.22
2014	4.33
2015	4.44