Year	Percent change (Units)
1981	-14.939
1982	-15.925
1983	-9.607
1984	-1.081
1985	-2.069
1986	22.172
1987	18.392
1988	7.627
1989	-1.808
1990	10.898
1991	-3.746
1992	6.100
1993	-15.104
1994	15.094
1995	22.652
1996	11.139
1997	-0.423
1998	4.787
1999	7.836
2000	12.709
2001	1.684
2002	0.272
2003	3.399
2004	12.087
2005	7.067
2006	9.045
2007	5.905
2008	1.534
2009	-15.377
2010	11.107
2011	8.411
2012	0.558
2013	0.709
2014	3.814
2015	4.995
2016	1.919
2017	4.155
2018	4.253
2019	6.608
2020	-5.781
2021	11.466
2022	6.949
2023	3.114
2024	1.385
2025	2.747
2026	3.606
2027	2.751
2028	5.018
2029	5.018