Year	Percent change (Units)
1980	11.073
1981	8.404
1982	-16.461
1983	-5.846
1984	10.944
1985	1.832
1986	16.848
1987	5.939
1988	-2.125
1989	1.938
1990	-3.465
1991	4.124
1992	10.020
1993	-2.597
1994	7.387
1995	2.996
1996	4.910
1997	26.171
1998	4.892
1999	26.992
2000	23.258
2002	-7.372
2003	-0.565
2004	19.380
2005	2.834
2006	4.558
2007	10.497
2008	3.891
2009	-19.181
2010	4.566
2011	0.547
2012	1.645
2013	12.926
2014	8.010
2015	5.463
2016	0.077
2017	7.803
2018	8.843
2019	3.395
2020	-22.674
2021	21.463
2022	9.124
2023	2.840
2024	1.847
2025	3.009
2026	3.086
2027	2.748
2028	2.748
2029	2.672