Year	Percent change (Units)
1980	2.405
1981	0.945
1982	-0.454
1983	1.410
1984	4.844
1985	0.464
1986	4.720
1987	2.671
1988	0.465
1989	-1.260
1990	-6.568
1991	-8.445
1992	-10.462
1993	-13.468
1994	-6.144
1995	2.762
1996	-1.935
1997	-7.840
1998	-3.875
1999	-3.802
2000	-8.136
2001	-2.100
2002	2.948
2003	6.633
2004	7.661
2005	9.804
2006	5.109
2007	8.530
2008	7.402
2009	0.565
2010	7.843
2011	7.593
2012	8.669
2013	9.624
2014	7.302
2015	6.360
2016	0.394
2017	3.658
2018	4.825
2019	4.485
2020	1.671
2021	6.037
2022	8.774
2023	6.140
2024	4.699
2025	5.658
2026	5.178
2027	5.808
2028	4.383
2029	4.079