Year	Percent
1960	1.19539
1961	1.78614
1962	2.3565
1963	2.82457
1964	3.1485
1965	3.33105
1966	3.54113
1967	3.67562
1968	3.46184
1969	2.83317
1970	1.97687
1971	1.02875
1972	0.24111
1973	-0.23635
1974	-0.26151
1975	0.0481
1976	0.45012
1977	0.76991
1978	1.07196
1979	1.31018
1980	1.49088
1981	1.71035
1982	1.93014
1983	2.02553
1984	1.96787
1985	1.81664
1986	1.6101
1987	1.46032
1988	1.45993
1989	1.65844
1990	1.97889
1991	2.3276
1992	2.58285
1993	2.72615
1994	2.71131
1995	2.5958
1996	2.44866
1997	2.33037
1998	2.21645
1999	2.12476
2000	2.04195
2001	1.96571
2002	1.87319
2003	1.76293
2004	1.62041
2005	1.46527
2006	1.30382
2007	1.16685
2008	1.08061
2009	1.06
2010	1.08492
2011	1.12486
2012	1.15691
2013	1.18502
2014	1.2099
2015	1.22265
2016	1.23958
2017	1.25754