Year	Percent change (Units)
1980	21.258
1981	21.614
1982	6.003
1983	2.658
1984	5.228
1985	-24.039
1986	22.110
1987	-4.870
1988	-0.691
1989	5.091
1990	-34.132
1991	0.320
1992	-38.605
1993	39.092
1994	-32.710
1995	1.457
1996	9.964
1997	15.277
1998	30.857
1999	8.568
2000	-10.145
2001	1.263
2002	12.406
2003	12.516
2004	6.556
2005	48.742
2006	-14.183
2007	9.603
2008	16.748
2009	-8.223
2010	24.963
2011	19.292
2012	-10.517
2013	-12.535
2014	-13.009
2015	3.999
2016	-3.876
2017	-3.745
2018	-0.024
2019	1.803
2020	-1.029
2021	-19.473
2022	43.442
2023	5.816
2024	-20.115
2025	6.948
2026	1.088
2027	-0.147
2028	4.824
2029	4.224