Year	Percent change (Units)
1980	9.596
1981	0.795
1982	4.059
1983	-6.067
1984	10.265
1985	1.151
1986	0.414
1987	-1.339
1988	3.445
1989	-0.202
1990	1.112
1991	2.100
1992	5.921
1993	0.445
1994	38.535
1995	14.458
1996	4.917
1997	3.803
1998	5.755
1999	0.348
2000	4.034
2001	3.757
2002	2.744
2003	1.814
2004	1.335
2005	4.658
2006	5.164
2007	1.252
2008	6.801
2009	0.738
2010	2.340
2011	2.847
2012	7.000
2013	0.967
2014	-1.067
2015	0.202
2016	-0.794
2017	1.769
2018	0.849
2019	-0.933
2020	3.049
2021	1.700
2022	1.400
2023	2.800
2024	3.000
2025	2.000
2026	2.000
2027	2.000
2028	2.000
2029	2.000