Year	Percent change (Units)
1980	10.946
1981	12.376
1982	0.426
1983	11.763
1984	8.577
1985	-6.507
1986	0.705
1987	-15.004
1988	5.377
1989	15.818
1990	-1.486
1991	31.596
1992	-43.556
1993	14.214
1994	10.841
1995	15.970
1996	0.758
1997	21.096
1998	10.899
1999	1.622
2000	-7.258
2001	0.728
2002	-0.610
2003	1.985
2004	9.217
2005	3.185
2006	-2.938
2007	-3.625
2008	-6.768
2009	-8.996
2010	-2.793
2011	-10.941
2012	-4.195
2013	0.625
2014	1.376
2015	16.111
2016	6.128
2017	-6.332
2018	-7.277
2019	4.967
2020	-10.439
2021	-8.529
2022	7.427
2023	7.722
2024	8.136
2025	6.257
2026	5.232
2027	4.998
2028	3.758
2029	3.890