Year	Percent change (Units)
1980	-6.588
1981	17.669
1982	6.867
1983	-27.426
1984	-44.407
1985	-32.411
1986	2.321
1987	5.486
1988	10.117
1989	-8.755
1990	-10.133
1991	12.809
1992	11.355
1993	32.171
1994	43.365
1995	23.316
1996	4.190
1997	5.629
1998	16.628
1999	0.468
2000	-0.928
2001	19.253
2002	12.283
2003	11.219
2004	-1.665
2005	0.736
2006	10.304
2007	15.180
2008	1.289
2009	-7.619
2010	-14.273
2011	-0.087
2012	6.750
2013	10.680
2014	15.533
2015	21.019
2016	6.976
2017	9.540
2018	-0.182
2019	11.772
2020	-15.734
2021	-0.369
2022	13.019
2023	15.831
2024	9.308
2025	10.539
2026	9.309
2027	7.780
2028	6.717
2029	6.462