Year	Percent
1961	13.63253
1962	6.26071
1963	4.76511
1964	3.05257
1965	6.55894
1966	2.57293
1967	1.99722
1968	0.32592
1969	5.79546
1970	6.46752
1971	8.13081
1972	9.2683
1973	8.1542
1974	36.84171
1975	16.8016
1976	32.75374
1977	-14.51443
1978	-25.7938
1979	-1.89804
1980	0.07392
1981	2.50473
1982	-5.53229
1983	2.90327
1984	4.70571
1985	-4.92168
1986	-3.47147
1987	-19.39828
1988	9.76653
1989	5.59758
1990	2.36527
1991	3.29097
1992	-5.64177
1993	1.24305
1994	1.0521
1995	2.31852
1996	1.03376
1997	3.11602
1998	0.92451
1999	-11.17364
2000	-4.3017
2001	-0.38421
2002	-2.72661
2003	-0.34991
2004	-1.97191
2005	-0.1719
2006	-5.61293
2007	2.85113
2008	-6.28001
2009	-3.04651
2010	3.59857
2011	3.50202
2012	1.67473
2013	2.12471
2014	1.06386
2015	0.94819
2016	-0.47568
2017	-1.15942