Year	Percent change (Units)
1980	6.552
1981	32.650
1982	2.370
1983	-6.747
1984	-8.867
1985	-23.273
1986	-22.366
1987	-9.726
1988	-15.913
1989	10.841
1990	11.100
1991	44.278
1992	-1.930
1993	-19.081
1994	-23.371
1995	7.607
1996	8.478
1997	10.362
1998	-11.223
1999	3.752
2000	18.914
2001	-7.048
2002	4.071
2003	5.815
2004	12.663
2005	24.555
2006	21.954
2007	21.324
2008	10.693
2009	-4.817
2010	-1.605
2011	5.511
2012	9.356
2013	10.032
2014	16.074
2015	3.154
2016	-16.574
2017	-0.609
2018	2.218
2019	3.269
2020	-16.114
2021	5.308
2022	10.487
2023	15.991
2024	9.043
2025	10.463
2026	4.305
2027	2.921
2028	1.723
2029	2.795