Year	Percent
1981	14.44283
1982	40.41801
1983	24.74977
1984	25.63717
1985	52.77479
1986	-2.92341
1987	1.51817
1988	3.97698
1989	-4.79586
1990	10.35253
1991	3.55211
1992	-15.4237
1993	-2.69312
1994	24.52635
1995	7.68083
1996	0.8212
1997	-13.14717
1998	-31.56591
1999	39.15763
2000	64.73502
2001	-11.97153
2002	-1.58289
2003	0.63562
2004	16.92276
2005	59.32905
2006	12.97637
2007	3.03765
2008	19.84004
2009	-20.83023
2010	24.90653
2011	17.04511
2012	4.85479
2013	-1.07268
2014	-1.27384
2015	-20.21117
2016	-6.35314
2017	12.52915