Year	Percent
1981	-42.39264
1982	-26.55738
1983	-33.6715
1984	-17.95031
1985	-29.18605
1986	-38.17439
1987	-23.11715
1988	-27.48068
1989	-38.28084
1990	-34.64052
1991	-42.86536
1992	-28.36534
1993	-30.19314
1994	-32.01935
1995	-22.30891
1996	-21.38817
1997	-26.92217
1998	-16.48303
1999	-6.41663
2000	-14.5425
2001	-19.37884
2002	-10.41284
2003	-5.26927
2004	-11.43681
2005	-20.53454
2006	-21.09746
2007	-22.37465
2008	-22.9
2009	-18.3
2010	-31.82232
2011	-11.54709
2012	-1.46633
2013	-9.75405
2014	-10.448
2015	-8.2443