Year	Percent
1980	0.4061
1981	1.46768
1982	-4.50254
1983	-2.61241
1984	-1.96426
1985	-2.21432
1986	-0.41
1987	-0.09621
1988	-2.83573
1989	-2.77822
1990	-8.32689
1991	-20.36723
1992	-77.02181
1993	-46.87002
1994	-27.59864
1995	-22.03667
1996	-20.82867
1997	-24.44434
1998	-23.79274
1999	-16.39629
2000	-20.18626
2001	-20.56722
2002	-24.73649
2003	-24.7288
2004	-22.39195
2005	-24.64715
2006	-23.58706
2007	-26.70398
2008	-26.8469
2009	-24.61343
2010	-20.58453
2011	-22.73555
2012	-18.6352
2013	-18.04107
2014	-18.98188
2015	-17.26625
2016	-16.82243
2017	-15.03152