Year	Percent change (Units)
1980	12.095
1981	-3.209
1982	36.554
1983	34.610
1984	31.292
1985	-10.922
1986	-25.565
1987	-48.336
1988	2.077
1989	1.432
1990	6.961
1991	16.625
1992	2.372
1993	-2.462
1994	9.339
1995	25.965
1996	14.879
1997	5.841
1998	-4.276
1999	3.700
2000	3.683
2001	-1.756
2002	-6.163
2003	-0.369
2004	3.202
2005	24.932
2006	37.094
2007	0.215
2008	-15.550
2009	-19.318
2010	8.710
2011	85.135
2012	-4.111
2013	-2.195
2014	1.457
2015	6.307
2016	8.958
2017	-4.352
2018	-6.283
2019	-0.278
2020	-16.974
2021	-4.484
2022	14.862
2023	0.419
2024	7.525
2025	3.084
2026	2.516
2027	3.654
2028	3.169
2029	3.325
