Year	Percent change
1981	-10.6
1982	39.8
1983	-11.6
1984	4.9
1985	-1.1
1986	-21.4
1987	-21.8
1988	19.6
1989	13.1
1990	-6
1991	0.54
1992	21.402
1993	-32.085
1994	-4.787
1995	-0.929
1996	-7.85
1997	29.65
1998	-24.582
1999	2.158
2000	18.803
2001	18.512
2002	-20.857
2003	-24.276
2004	49.862
2005	-10.591
2006	2.771
2007	34.719
2008	9.117
2009	-1.916
2010	2.947
2011	4.079
2012	-24.545
2013	-6.933
2014	26.85
2015	8.898
2016	18.619
2017	24.955
2018	-11.845
2019	22.124
2020	6.764
2021	7.296
2022	7.84
2023	7.853
2024	8.138