Year	Percent change (Units)
1980	20.636
1981	-2.231
1982	-7.577
1983	-0.699
1984	7.899
1985	-11.414
1986	-0.035
1987	6.186
1988	10.327
1989	9.843
1990	1.755
1991	3.681
1992	0.977
1993	11.318
1994	10.599
1995	15.356
1996	8.327
1997	18.666
1998	9.776
1999	-41.153
2000	22.435
2001	-2.492
2002	11.174
2003	9.715
2004	8.276
2005	-1.636
2006	13.082
2007	-2.517
2008	-0.642
2009	-9.160
2010	17.952
2011	3.781
2012	20.004
2013	-5.271
2014	14.633
2015	-6.949
2016	5.991
2017	24.623
2018	3.904
2019	3.466
2020	-11.314
2021	9.132
2022	6.459
2023	-2.449
2024	-3.378
2025	4.926
2026	6.116
2027	6.727
2028	6.026
2029	2.144