Year	Percent change (Units)
1980	33.124
1981	-17.836
1982	-10.009
1983	3.312
1984	32.775
1985	5.045
1986	-3.568
1987	1.138
1988	2.005
1989	-14.931
1990	24.929
1991	5.344
1992	-2.903
1993	-5.105
1994	10.287
1995	-0.307
1996	16.899
1997	4.350
1998	24.399
1999	-16.568
2000	-6.753
2001	4.535
2002	6.287
2003	6.387
2004	9.660
2005	-10.568
2006	10.601
2007	43.617
2008	7.846
2009	-29.541
2010	37.062
2011	-9.400
2012	0.681
2013	21.996
2014	3.179
2015	-22.383
2016	-7.294
2017	-11.509
2018	2.227
2019	8.092
2020	-19.881
2021	27.453
2022	-16.007
2023	23.562
2024	4.009
2025	8.034
2026	5.462
2027	9.310
2028	5.974
2029	4.622