Year	Percent change (Units)
1981	15.353
1982	0.934
1983	-30.968
1984	24.584
1985	-8.531
1986	63.442
1987	83.915
1988	15.381
1989	-35.438
1990	11.646
1991	66.153
1992	-56.506
1993	33.039
1994	36.455
1995	-45.982
1996	149.574
1997	-33.231
1998	24.523
1999	18.370
2000	-35.725
2001	-38.490
2002	72.527
2003	-3.771
2004	-15.358
2005	107.891
2006	131.168
2007	40.950
2008	20.231
2009	-10.247
2010	29.520
2011	-19.383
2012	23.810
2013	-17.663
2014	-5.643
2015	-15.453
2016	-16.286
2017	8.330
2018	6.197
2019	-11.239
2020	-10.829
2021	12.540
2022	-52.600
2023	-21.507
2024	0.534
2025	8.622
2026	-6.597
2027	1.923
2028	4.787
2029	-1.053