Year	Percent change (Units)
1980	2.978
1981	7.116
1982	-0.570
1983	-9.696
1984	9.145
1985	9.419
1986	0.949
1987	23.265
1988	-4.585
1989	-10.257
1990	0.991
1991	5.259
1992	-5.972
1993	-7.501
1994	3.821
1995	3.617
1996	14.599
1997	6.880
1998	21.945
1999	3.352
2000	7.802
2001	-9.976
2002	-2.731
2003	10.255
2004	14.622
2005	27.827
2006	9.820
2007	-2.263
2008	-20.313
2009	-20.670
2010	2.319
2011	6.774
2012	4.604
2013	0.106
2014	10.020
2015	13.542
2016	14.603
2017	11.831
2018	-0.908
2019	-9.088
2020	-20.635
2021	19.905
2022	19.970
2023	-1.439
2024	1.163
2025	1.851
2026	2.364
2027	2.654
2028	2.596
2029	2.828