Year	Percent change (Units)
1981	-0.694
1982	9.407
1983	-12.484
1984	-10.123
1985	34.660
1986	20.952
1987	-3.806
1988	-6.213
1989	-10.056
1990	13.504
1991	-6.243
1992	-8.282
1993	8.428
1994	-26.981
1995	15.027
1996	15.454
1997	-2.486
1998	31.509
1999	-13.484
2000	-13.571
2001	1.738
2002	7.565
2003	18.854
2004	-3.475
2005	-0.183
2006	4.296
2007	12.083
2008	11.303
2009	-6.509
2010	8.034
2011	10.619
2012	14.980
2013	15.946
2014	-6.763
2015	7.411
2016	2.939
2017	14.278
2018	4.381
2019	-2.658
2020	1.395
2021	14.609
2022	4.485
2023	2.484
2024	4.851
2025	3.753
2026	4.015
2027	4.364
2028	4.599
2029	4.814