Year	Percent change (Units)
1981	-10.152
1982	-3.126
1983	5.579
1984	10.343
1985	-22.469
1986	-4.591
1987	-15.943
1988	-7.020
1989	13.665
1990	44.265
1991	-20.191
1992	-47.432
1993	57.813
1994	24.911
1995	12.383
1996	46.177
1997	18.477
1998	-1.333
1999	-12.231
2000	13.911
2001	-0.898
2002	-18.079
2003	2.524
2004	62.057
2005	24.873
2006	9.505
2007	9.062
2008	-1.452
2009	1.420
2010	23.589
2011	14.465
2012	6.204
2013	3.575
2014	6.497
2015	-2.422
2016	6.721
2017	-2.140
2018	-0.497
2019	-5.728
2020	2.240
2021	12.590
2022	2.485
2023	-17.280
2024	14.902
2025	30.132
2026	13.615
2027	10.267
2028	10.285
2029	3.196