Year	Percent change (Units)
1980	193.663
1981	-16.754
1982	43.328
1983	-35.057
1984	-26.079
1985	-22.806
1986	24.488
1987	4.217
1988	-17.082
1989	3.286
1990	1.610
1991	1.942
1992	2.004
1993	2.193
1994	-1.709
1995	-1.391
1996	-1.818
1997	17.424
1998	-3.715
1999	16.926
2000	-1.468
2001	9.765
2002	-13.623
2003	74.476
2004	-5.260
2005	3.420
2006	2.975
2007	3.990
2008	18.872
2009	5.389
2010	-10.008
2011	5.361
2012	-12.094
2013	0.741
2014	-6.022
2015	20.853
2016	1.070
2017	-4.401
2018	-3.059
2019	-3.163
2020	-50.092
2021	0.784
2022	13.641