Year	Percent
1980	-24.05755
1981	-32.59866
1982	-33.99841
1983	-33.71286
1984	-32.19959
1985	-36.14463
1986	-34.79043
1987	-14.54418
1988	-21.0436
1989	-9.91969
1990	-3.82224
1991	-7.96459
1992	-23.91737
1993	-12.52521
1994	-9.8973
1995	-4.86059
1996	-10.18019
1997	-10.21126
1998	-16.31758
1999	-19.58669
2000	-18.91039
2001	-21.46198
2002	-25.45717
2003	-25.29926
2004	-31.13692
2005	-26.19859
2006	-4.75842
2007	-2.32695
2008	-9.16893
2009	-17.50216
2010	-28.27841
2011	-29.28075
2012	-24.31326
2013	-21.81567
2014	-21.05335
2015	-28.5065
2016	-23.37516
2017	-21.95063