Year	Percent change (Units)
1980	21.616
1981	14.216
1982	-17.849
1983	-18.680
1984	21.473
1985	-14.699
1986	-5.324
1987	3.961
1988	23.943
1989	-1.540
1990	-4.265
1991	0.381
1992	5.539
1993	6.695
1994	18.917
1995	19.676
1996	11.852
1997	6.732
1998	1.222
1999	-9.288
2000	7.733
2001	0.155
2002	5.613
2003	4.649
2004	17.895
2005	11.776
2006	19.888
2007	10.046
2008	4.079
2009	-21.394
2010	9.743
2011	14.677
2012	6.511
2013	5.119
2014	-0.147
2015	5.055
2016	-4.529
2017	2.118
2018	4.823
2019	0.812
2020	-15.421
2021	10.018
2022	12.582
2023	4.104
2024	4.005
2025	3.890
2026	3.832
2027	3.836
2028	3.836
2029	3.836