Year	Percent change (Units)
1981	12.508
1982	23.522
1983	9.575
1984	22.776
1985	-13.473
1986	29.567
1987	1.620
1988	6.230
1989	-4.008
1990	-12.999
1991	-1.275
1992	76.284
1993	11.786
1994	40.940
1995	-9.725
1996	4.476
1997	50.853
1998	-21.563
1999	18.296
2000	-10.019
2001	34.805
2002	-7.716
2003	38.824
2004	6.129
2005	24.251
2006	-4.457
2007	-1.449
2008	21.403
2009	-4.652
2010	23.428
2011	-9.364
2012	5.926
2013	10.115
2014	39.436
2015	-0.734
2016	32.408
2017	0.888
2018	-1.560
2019	6.098
2020	-9.000
2021	-22.456
2022	22.215
2023	53.449
2024	8.418
2025	13.289
2026	5.941
2027	6.677
2028	5.171
2029	4.443