Year	Percent change (Units)
1980	9.668
1981	14.610
1982	6.593
1983	7.835
1984	6.310
1985	10.432
1986	14.007
1987	5.857
1988	5.938
1989	9.172
1990	9.272
1991	25.900
1992	31.700
1993	20.500
1994	29.000
1995	29.800
1996	18.700
1997	5.700
1998	4.950
1999	2.600
2000	0.300
2001	4.200
2002	1.433
2003	4.261
2004	3.968
2005	1.382
2006	2.311
2007	3.679
2008	4.855
2009	5.741
2010	3.911
2011	4.500
2012	8.916
2013	3.255
2014	2.917
2015	4.784
2016	6.398
2017	5.591
2018	4.270
2019	1.952
2020	2.415
2021	7.226
2022	9.267
2023	9.320
2024	7.551
2025	6.352
2026	6.080
2027	5.519
2028	5.230
2029	5.015