Year	Percent change
1981	19.399
1982	-17.799
1983	15.375
1984	-6.695
1985	-0.823
1986	-33.674
1987	-18.385
1988	-12.849
1989	-10.209
1990	9.126
1991	16.27
1992	19.032
1993	25.227
1994	30.066
1995	-21.058
1996	13.438
1997	-16.812
1998	-1.686
1999	11.06
2000	-1.697
2001	26.184
2002	5.607
2003	18.983
2004	6.266
2005	6.061
2006	-26.771
2007	15.999
2008	24.478
2009	19.267
2010	5.353