Year	Percent change (Units)
1980	14.945
1981	0.747
1982	-8.625
1983	-22.541
1984	6.158
1985	12.145
1986	4.419
1987	4.729
1988	-22.307
1989	20.487
1990	-7.900
1991	14.951
1992	19.312
1993	9.506
1994	10.103
1995	5.872
1996	10.775
1997	14.954
1998	5.395
1999	-4.776
2000	-9.926
2001	-5.004
2002	1.136
2003	-1.617
2004	12.214
2005	8.089
2006	4.415
2007	20.316
2008	15.109
2009	-15.406
2010	27.743
2011	29.495
2012	-4.462
2013	-0.343
2014	-2.307
2015	-1.254
2016	2.273
2017	5.119
2018	0.051
2019	-9.335
2020	-28.218
2021	30.591
2022	26.406
2023	-7.664
2024	8.636
2025	8.204
2026	4.416
2027	1.566
2028	4.455
2029	4.088