Year	Percent change (Units)
1980	-86.683
1981	-17.200
1982	76.500
1983	-31.800
1984	55.700
1985	-1.300
1986	8.100
1987	63.300
1988	-20.800
1989	-8.500
1990	4.200
1991	18.100
1992	-22.300
1993	32.700
1994	452.100
1995	23.200
1996	13.500
1997	0.000
1999	-25.968
2000	25.213
2001	3.042
2002	12.189
2003	14.478
2004	-21.245
2005	28.280
2006	6.497
2007	185.990
2008	-61.681
2009	10.248
2010	29.683
2011	35.674
2012	-10.344
2013	17.036
2014	53.521
2015	-16.973
2016	10.811
2017	-7.045
2018	20.560
2019	4.517
2020	-29.146
2021	-4.584
2022	4.070
2023	29.878
2024	9.637
2025	19.139
2026	17.204
2027	14.382
2028	10.884
2029	8.728