Year	Percent change (Units)
1980	14.100
1981	-2.409
1982	-29.652
1983	-5.902
1984	18.591
1985	-6.604
1986	-23.329
1987	-15.046
1988	28.270
1989	3.689
1990	-8.881
1991	-20.494
1992	-9.962
1993	27.344
1994	11.374
1995	-5.891
1996	-21.202
1997	9.579
1998	-27.845
1999	-22.490
2000	-26.869
2001	-12.610
2002	-29.122
2003	-4.746
2004	18.763
2005	45.952
2006	41.854
2007	27.601
2008	-2.552
2009	-0.950
2010	44.131
2011	-1.358
2012	4.666
2013	11.748
2014	-2.400
2015	6.082
2016	3.880
2017	1.924
2018	3.246
2019	3.298
2020	-21.052
2021	-8.810
2022	6.673
2023	13.598
2024	-6.296
2025	8.807
2026	6.742
2027	4.047
2028	2.505
2029	2.406