Year	Percent
1960	0.69012
1961	1.48363
1962	1.33381
1963	1.33561
1964	1.33457
1965	1.12265
1966	0.7605
1967	0.7854
1968	0.96865
1969	0.83801
1970	0.68013
1971	0.72748
1972	0.80825
1973	0.83737
1974	0.88057
1975	0.77428
1976	0.60315
1977	0.56836
1978	0.51568
1979	0.32103
1980	0.22911
1981	0.30689
1982	0.4617
1983	0.58817
1984	0.62787
1985	0.65459
1986	0.81174
1987	1.02139
1988	1.01709
1989	0.50827
1990	-0.14274
1991	-0.47311
1992	-1.3768
1993	-1.97193
1994	-1.67383
1995	-1.42581
1996	-1.12638
1997	-0.99676
1998	-0.94292
1999	-0.81396
2000	-0.96394
2001	-1.29149
2002	-1.16184
2003	-0.9664
2004	-1.09131
2005	-1.08057
2006	-0.91727
2007	-0.81618
2008	-1.05094
2009	-1.65102
2010	-2.08131
2011	-1.82077
2012	-1.24036
2013	-1.07103
2014	-0.94174
2015	-0.81863
2016	-0.91389
2017	-0.96389