Year	Percent change (Units)
1980	38.319
1981	-20.338
1982	-9.508
1983	3.680
1984	33.385
1985	4.666
1986	-2.100
1987	1.618
1988	1.556
1989	-15.682
1990	26.211
1991	5.888
1992	-0.846
1993	-4.753
1994	9.529
1995	1.735
1996	15.613
1997	4.518
1998	23.870
1999	-20.644
2000	-6.574
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