Year	Percent change (Units)
1981	1.700
1982	-0.600
1983	-23.600
1984	48.400
1985	-27.400
1986	-4.900
1987	39.500
1988	21.200
1989	-13.100
1990	32.800
1991	5.903
1992	-70.657
1993	164.628
1994	134.584
1995	-31.699
1996	-12.906
1997	115.636
1998	-19.790
1999	63.178
2000	21.655
2001	10.315
2002	-11.709
2003	-2.191
2004	11.110
2005	14.451
2006	-12.394
2007	17.776
2008	0.981
2009	19.392
2010	-7.451
2011	40.971
2012	-13.336
2013	5.143
2014	8.027
2015	6.699
2016	0.806
2017	6.392
2018	35.527
2019	13.527
2020	-13.785
2021	25.480
2022	-23.620
2023	5.727
2024	18.414
2025	1.649
2026	2.861
2027	2.677
2028	3.088
2029	2.633