Year	Percent
1960	3.59639
1961	3.5317
1962	3.44426
1963	3.33025
1964	3.19373
1965	3.04492
1966	2.88453
1967	2.73434
1968	2.61671
1969	2.5406
1970	2.49171
1971	2.4505
1972	2.39705
1973	2.3232
1974	2.22248
1975	2.10513
1976	1.98604
1977	1.87871
1978	1.7851
1979	1.70992
1980	1.64737
1981	1.54748
1982	1.43792
1983	1.39635
1984	1.44085
1985	1.52052
1986	1.67422
1987	1.74418
1988	1.5154
1989	0.90378
1990	0.04795
1991	-0.93461
1992	-1.79741
1993	-2.34254
1994	-2.39039
1995	-2.04031
1996	-1.53872
1997	-1.11499
1998	-0.7819
1999	-0.63466
2000	-0.63096
2001	-0.6187
2002	-0.55084
2003	-0.53179
2004	-0.57138
2005	-0.64706
2006	-0.76633
2007	-0.86375
2008	-0.85037
2009	-0.67748
2010	-0.39102
2011	-0.06014
2012	0.22027
2013	0.40125
2014	0.43833
2015	0.36853
2016	0.2693
2017	0.19244