Year	Percent
1970	1.88762
1971	1.23942
1972	0.81654
1973	1.08478
1974	1.61889
1975	1.48675
1976	1.42882
1977	0.73129
1978	2.52504
1979	1.4498
1980	-1.69624
1981	0.67327
1982	0.36148
1983	0.17057
1984	0.53856
1985	-3.61271
1986	-28.62426
1987	5.61944
1988	-2.18831
1989	2.39625
1990	4.99268
1991	0.96213
1992	-0.82339
1993	-0.97071
1994	-0.31518
1995	0.83686
1996	0.0705
1997	0.21171
1998	0.0156
1999	0.07966
2000	6.13342
2001	0.90197
2002	0.83085
2003	0.62166
2004	4.22173
2005	5.49724
2006	3.12285
2007	4.42299
2008	2.11918
2009	4.50019
2010	9.24755
2011	32.30119
2012	19.00246
2013	8.73241
2014	7.47912
2015	5.9837
2016	3.87976
2017	14.8373