Year	Percent
1970	0.28824
1971	0.20522
1972	0.13531
1973	0.14336
1974	0.11768
1975	0.09816
1976	0.00552
1977	0.08746
1978	0.0677
1979	0.09246
1980	0.17911
1981	0.14165
1982	0.31482
1983	0.21799
1984	0.26938
1985	0.34925
1986	0.72967
1987	0.35427
1988	0.82003
1989	0.84328
1990	0.76792
1991	2.34902
1992	-0.00193
1993	1.76466
1994	2.77282
1995	5.65774
1996	1.90622
1997	3.88353
1998	7.50271
1999	22.38404
2000	8.78278
2001	7.59337
2002	6.96469
2003	1.81441
2004	4.41562
2005	5.34201
2006	5.25023
2007	9.4592
2008	8.06213
2009	2.08559
2010	0.128
2011	1.23943
2012	0.78575
2013	0.22757
2014	-1.50296
2015	1.74849
2016	1.57608
2017	6.05036