Year	Percent change (Units)
1980	13.039
1981	-10.568
1982	14.494
1983	-4.552
1984	14.735
1985	-3.719
1986	-7.919
1987	-45.620
1988	-10.517
1989	14.154
1990	-3.553
1991	38.802
1992	-3.904
1993	9.168
1994	-0.976
1995	18.906
1996	-13.505
1997	7.182
1998	3.482
1999	-11.042
2000	15.818
2001	8.396
2002	8.837
2003	2.908
2004	17.913
2005	8.737
2006	13.858
2007	14.530
2008	4.712
2009	-0.972
2010	-9.250
2011	-4.297
2012	-15.486
2013	10.529
2014	-5.982
2015	9.112
2016	4.453
2017	9.999
2018	9.131
2019	6.428
2020	3.703
2021	5.326
2022	20.490
2023	-9.420
2024	-14.057
2025	6.594
2026	10.488
2027	10.094
2028	9.833
2029	7.498