Year	Percent change (Units)
1980	-0.994
1981	4.054
1982	5.195
1983	-4.938
1984	16.883
1985	11.111
1986	5.000
1987	-0.952
1988	-2.885
1989	1.980
1990	16.500
1991	1.200
1992	4.000
1993	14.300
1994	9.400
1995	7.160
1996	4.147
1997	10.619
1998	-1.500
1999	5.076
2000	18.261
2001	11.341
2002	-13.515
2003	8.383
2004	7.700
2005	-0.578
2006	4.667
2007	2.310
2008	-2.271
2009	-16.346
2010	13.791
2011	-11.016
2012	-8.300
2013	16.068
2014	13.430
2015	4.733
2016	9.116
2017	4.461
2018	5.794
2019	-2.245
2020	-29.777
2021	2.287
2022	-3.033