Year	Percent change (Units)
1980	0.752
1981	-2.260
1982	-7.285
1983	2.859
1984	8.028
1985	0.722
1986	5.536
1987	4.765
1988	3.432
1989	5.666
1990	3.600
1991	2.263
1992	9.201
1993	7.097
1994	4.519
1995	4.154
1996	1.350
1997	5.476
1998	7.155
1999	4.215
2000	3.869
2001	3.491
2002	3.417
2003	4.317
2004	4.425
2005	3.977
2006	7.327
2007	8.215
2008	4.738
2009	-0.873
2010	5.360
2011	4.403
2012	4.883
2013	2.495
2014	3.542
2015	3.652
2016	4.204
2017	4.158
2018	2.616
2019	2.418
2020	-4.273
2021	7.936
2022	4.551
2023	5.112
2024	3.999
2025	3.504
2026	3.304
2027	3.300
2028	3.300
2029	3.300