Year	Percent
1981	4.55114
1982	2.03229
1983	3.17252
1984	3.15481
1985	2.68495
1986	4.23524
1987	5.89861
1988	10.82009
1989	-2.15169
1990	-7.46321
1991	-7.53407
1992	-6.27126
1993	-0.69121
1994	2.16436
1995	3.31935
1996	1.22539
1997	-0.48481
1998	4.15545
1999	-5.48141
2000	5.46013
2001	5.8566
2002	8.26224
2003	5.99248
2004	7.24177
2005	7.93317
2006	7.68917
2007	8.13662
2008	6.76869
2009	-2.96296
2010	1.99328
2011	2.57051
2012	0.61205
2013	1.42822
2014	1.90634
2015	4.28072
2016	4.67268
2017	4.32022