Year	Percent change (Units)
1980	-2.663
1981	-1.797
1982	-1.670
1983	3.891
1984	0.170
1985	-3.132
1986	-0.201
1987	8.421
1988	1.250
1989	4.264
1990	2.200
1991	6.000
1992	12.700
1993	4.000
1994	8.100
1995	10.089
1996	1.610
1997	-0.914
1998	1.292
1999	-0.486
2000	-14.277
2001	-7.957
2002	-2.800
2003	6.523
2004	6.667
2005	5.526
2006	4.874
2007	4.442
2008	5.806
2009	2.569
2010	8.616
2011	7.267
2012	1.367
2013	5.237
2014	1.186
2015	1.678
2016	5.556
2017	3.077
2018	2.745
2019	1.749
2020	-3.383
2021	2.564
2022	2.403
2023	2.950
2024	2.372
2025	2.530
2026	2.619
2027	2.919
2028	2.942
2029	2.964