Year	Percent change (Units)
1981	-20.960
1982	-15.832
1983	-17.433
1984	-1.951
1985	3.431
1986	25.522
1987	19.906
1988	9.655
1989	1.608
1990	10.592
1991	-7.646
1992	5.365
1993	-18.114
1994	14.259
1995	19.640
1996	9.203
1997	-0.057
1998	6.993
1999	5.007
2000	13.024
2001	-2.123
2002	-1.819
2003	4.048
2004	7.302
2005	8.383
2006	8.125
2007	9.519
2008	2.857
2009	-14.189
2010	11.816
2011	7.314
2012	0.122
2013	1.023
2014	6.553
2015	5.031
2016	4.803
2017	4.464
2018	4.146
2019	2.387
2020	-5.906
2021	11.721
2022	9.324
2023	0.968
2024	1.273
2025	2.552
2026	2.479
2027	2.596
2028	5.060
2029	5.060