Year	Percent
1968	2.36944
1969	-1.14688
1970	4.57349
1971	0.94872
1972	4.07185
1973	-3.16777
1974	-3.26313
1975	9.66317
1976	11.65137
1977	4.51668
1978	-3.17844
1979	8.40751
1980	-6.12792
1981	-0.51423
1982	-9.30107
1983	-0.28589
1984	-2.23009
1985	18.16374
1986	1.10127
1987	-1.53283
1988	5.90675
1989	2.56257
1990	-4.29517
1991	9.32593
1992	-5.57318
1993	0.4844
1994	1.02923
1995	-1.7171
1996	4.31488
1997	2.16237
1998	4.80756
1999	2.8969
2000	-2.83063
2001	12.05011
2002	0.0441
2003	5.79052
2004	-1.60991
2005	3.14815
2006	1.27316
2007	0.09916
2008	1.34514
2009	1.32238
2010	2.13752
2011	0.14521
2012	-3.72115
2013	-0.62157
2014	3.98261
2015	2.89883
2016	2.70192
2017	2.19277