Year	Percent change (Units)
1980	7.594
1981	0.734
1982	-2.270
1983	9.947
1984	13.340
1985	-4.477
1986	23.242
1987	28.122
1988	24.702
1989	6.790
1990	5.185
1991	15.016
1992	9.425
1993	6.944
1994	4.862
1995	10.303
1996	5.313
1997	13.357
1998	7.412
1999	4.127
2000	15.086
2001	-14.261
2002	5.767
2003	7.356
2004	17.840
2005	2.778
2006	4.562
2007	3.516
2008	-1.478
2009	-14.711
2010	30.629
2011	1.745
2012	21.599
2013	1.203
2014	1.889
2015	-0.746
2016	-5.347
2017	3.186
2018	1.525
2019	2.343
2020	-3.287
2021	17.375
2022	1.513
2023	-6.511
2024	4.630
2025	2.850
2026	2.490
2027	2.560
2028	2.840
2029	2.560