Year	Percent change (Units)
1980	30.000
1981	18.769
1982	4.023
1983	20.100
1984	19.400
1985	12.300
1986	11.800
1987	14.500
1988	-5.296
1989	5.257
1990	34.533
1991	-4.405
1992	7.463
1993	37.021
1994	-25.965
1995	29.453
1996	29.290
1997	21.741
1998	-2.260
1999	-1.427
2000	32.848
2001	-24.805
2002	20.719
2003	19.273
2004	20.575
2005	12.209
2006	8.443
2007	12.714
2008	-1.363
2009	-12.931
2010	17.719
2011	12.894
2012	0.934
2013	7.300
2014	-1.108
2015	2.442
2016	3.338
2017	9.840
2018	-9.124
2019	-5.052
2020	10.703
2021	1.653
2022	8.568
2023	11.720
2024	6.557
2025	2.402
2026	1.877
2027	2.675
2028	2.635
2029	2.575