Year	Years
1970	1.2
1971	1.23
1972	1.27
1973	1.31
1974	1.35
1975	1.39
1976	1.43
1977	1.47
1978	1.52
1979	1.56
1980	1.61
1981	1.66
1982	1.7
1983	1.75
1984	1.8
1985	1.86
1986	1.91
1987	1.96
1988	2.02
1989	2.08
1990	2.13
1991	2.19
1992	2.25
1993	2.32
1994	2.38
1995	2.45
1996	2.52
1997	2.59
1998	2.67
1999	2.74
2000	2.82
2001	2.9
2002	2.99
2003	3.07
2004	3.16
2005	3.25
2006	3.34
2007	3.43
2008	3.53
2009	3.63
2010	3.73
2011	3.83
2012	3.94
2013	4.05
2014	4.16
2015	4.27