Year	Percent change (Units)
1981	23.645
1982	-0.373
1983	6.554
1984	0.527
1985	-4.983
1986	-4.231
1987	0.192
1988	-4.603
1989	1.608
1990	-2.572
1991	-6.904
1992	-2.615
1993	3.471
1994	40.585
1995	7.644
1996	3.632
1997	4.114
1998	3.358
1999	-1.426
2000	4.353
2001	3.050
2002	0.602
2003	-1.512
2004	3.691
2005	4.164
2006	0.328
2007	4.746
2008	13.594
2009	-4.299
2010	2.677
2011	1.413
2012	0.707
2013	1.099
2014	-0.579
2015	2.130
2016	-2.156
2017	1.747
2018	1.618
2019	-2.317
2020	3.063
2021	4.890
2022	3.108
2023	7.181
2024	3.603
2025	5.126
2026	2.500
2027	2.000
2028	2.000
2029	2.000