Year	Percent change (Units)
1980	23.375
1981	3.672
1982	-14.273
1983	-10.598
1984	-9.591
1985	0.834
1986	34.493
1987	19.461
1988	4.608
1989	15.249
1990	19.656
1991	-8.358
1992	8.315
1993	11.110
1994	-7.449
1995	0.040
1996	12.345
1997	14.949
1998	5.284
1999	8.466
2000	5.787
2001	-18.664
2002	13.914
2003	-6.583
2004	-12.897
2005	24.303
2006	10.243
2007	-16.140
2008	-5.584
2009	21.938
2010	7.269
2011	-3.328
2012	-11.213
2013	-8.302
2014	3.434
2015	-1.360
2016	59.677
2017	-4.624
2018	4.375
2019	-19.071
2020	-15.652
2021	5.346
2022	17.641
2023	3.492
2024	5.220
2025	2.342
2026	3.451
2027	3.992
2028	4.200
2029	3.593