Year	Percent change (Units)
1980	4.318
1981	14.318
1982	-3.238
1983	-24.475
1984	-21.586
1985	-21.787
1986	81.347
1987	20.549
1988	-17.184
1989	15.889
1990	0.525
1991	0.610
1992	0.643
1993	0.653
1994	-11.725
1995	0.161
1996	-10.149
1997	-24.586
1998	-3.102
1999	3.270
2000	2.888
2001	27.156
2002	61.617
2003	29.726
2004	11.115
2005	1.368
2006	9.630
2007	15.198
2008	12.267
2009	-7.294
2010	-7.994
2011	0.146
2012	2.790
2013	-4.344
2014	-8.600
2015	-3.181
2016	-0.067
2017	-0.229
2018	-7.678
2019	23.438
2020	-21.805
2021	3.423
2022	-7.918