Year	Percent change
1981	-25.9
1982	38.5
1983	-10.6
1984	11.3
1985	2.4
1986	-17.4
1987	-18.3
1988	12.7
1989	13.1
1990	-12.7
1991	0.54
1992	21.402
1993	-32.085
1994	-4.787
1995	-0.929
1996	-7.85
1997	29.65
1998	-30.413
1999	12.216
2000	12.98
2001	12.845
2002	-9.154
2003	-14.858
2004	34.57
2005	-12.634
2006	10.71
2007	40.897
2008	9.228
2009	0.076
2010	7.312
2011	-0.521
2012	-24.5
2013	-1.405
2014	30.455
2015	15.735
2016	14.645
2017	18.61
2018	-7.13
2019	16.329
2020	4.957
2021	5.472
2022	6.027
2023	6.197
2024	6.594