Year	Percent change (Units)
1981	-22.246
1982	3.341
1983	-5.122
1984	9.441
1985	-12.687
1986	12.701
1987	-5.948
1988	-33.657
1989	14.248
1990	9.758
1991	6.716
1992	4.624
1993	9.500
1994	23.770
1995	0.521
1996	-2.125
1997	-29.691
1998	15.345
1999	16.276
2000	-6.264
2001	45.067
2002	-10.013
2003	-23.438
2004	-16.652
2005	74.851
2006	-9.976
2007	-1.299
2008	26.816
2009	-3.069
2010	-11.408
2011	17.937
2012	3.402
2013	-2.055
2014	6.768
2015	-3.607
2016	-32.889
2017	-3.763
2018	-4.793
2019	6.494
2020	-18.467
2021	38.677
2022	14.169
2023	5.729
2024	21.506
2025	7.509
2026	6.233
2027	6.070
2028	7.460
2029	6.489