Year	Percent change (Units)
1980	-69.883
1981	-10.111
1982	135.474
1983	2.765
1984	-18.869
1985	-9.384
1986	-12.401
1987	27.568
1988	11.072
1989	7.881
1990	20.700
1991	10.682
1992	9.651
1993	15.793
1994	1.348
1995	-17.899
1996	-5.053
1997	-13.101
1998	8.559
1999	-1.627
2000	11.243
2001	-2.055
2002	13.601
2003	18.584
2004	-1.373
2005	-5.447
2006	4.026
2007	-3.130
2008	-3.781
2009	6.893
2010	7.938
2011	-1.127
2012	-2.195
2013	-19.839
2014	21.036
2015	45.823
2016	14.408
2017	0.100
2018	-15.012
2019	-19.633
2020	-4.371
2021	14.523
2022	3.530
2023	17.563
2024	7.447
2025	8.408
2026	3.977
2027	2.465
2028	2.076
2029	2.294