Year	Percent
1980	14.03913
1981	-11.35116
1982	-8.53322
1983	-7.57139
1984	-6.14859
1985	11.44751
1986	10.2892
1987	-4.88607
1988	1.49652
1989	3.34358
1990	-6.60413
1991	-5.83961
1992	-5.91129
1993	-2.91775
1994	-1.29305
1995	-4.22154
1996	-5.79869
1997	-7.64537
1998	-9.50489
1999	-8.34644
2000	-3.67267
2001	-6.49147
2002	-2.06997
2003	-9.08466
2004	-2.26718
2005	0.13691
2006	3.90842
2007	-5.33518
2008	-12.49878
2009	-20.78404
2010	-12.89892
2011	-11.94885
2012	-16.74346
2013	-16.86483
2014	-24.71459
2015	-30.29872
2016	-22.82808
2017	-10.82127