Year	Percent change (Units)
1980	23.095
1981	5.854
1982	8.058
1983	-6.017
1984	0.273
1985	-2.437
1986	3.508
1987	1.753
1988	-8.826
1989	-19.927
1990	41.683
1991	4.024
1992	-52.047
1993	43.369
1994	-32.477
1995	145.712
1996	0.175
1997	10.922
1998	27.495
1999	16.807
2000	-1.271
2001	1.225
2002	-3.516
2003	8.968
2004	-1.226
2005	8.529
2006	9.799
2007	6.882
2008	7.923
2009	6.042
2010	43.786
2011	-4.972
2012	-7.438
2013	8.707
2014	16.905
2015	8.980
2016	-8.463
2017	9.007
2018	5.429
2019	-9.660
2020	-6.157
2021	3.973
2022	-5.968
2023	1.965
2024	-3.061
2025	5.680
2026	2.026
2027	2.082
2028	2.042
2029	2.028