Year	Percent change (Units)
1980	14.286
1981	13.194
1982	13.804
1983	10.512
1984	12.439
1985	9.111
1986	3.380
1987	4.423
1988	3.131
1989	4.464
1990	0.721
1991	11.700
1992	9.450
1993	7.474
1994	10.671
1995	8.342
1996	3.996
1997	3.586
1998	3.719
1999	2.574
2000	-2.907
2001	-8.839
2002	-9.863
2003	-2.057
2004	1.252
2005	2.658
2006	1.465
2007	6.211
2008	10.401
2009	2.448
2010	2.458
2011	15.902
2012	6.072
2013	2.594
2014	2.433
2015	10.011
2016	25.872
2017	25.860
2018	13.974
2019	-2.870
2020	1.468
2021	2.880
2022	4.510
2023	3.428
2024	2.863
2025	2.863
2026	2.863
2027	2.863
2028	2.564
2029	2.564