Year	Percent change (Units)
1980	1.845
1981	-11.927
1982	9.335
1983	18.226
1984	14.202
1985	-3.566
1986	9.795
1987	16.178
1988	13.264
1989	18.059
1990	15.000
1991	16.573
1992	13.442
1993	9.916
1994	20.701
1995	19.022
1996	4.803
1997	4.534
1998	4.547
1999	14.104
2000	12.710
2001	-4.405
2002	7.378
2003	10.115
2004	20.149
2005	4.681
2006	6.360
2007	-7.326
2008	-11.821
2009	-12.963
2010	10.075
2011	5.251
2012	-3.844
2013	1.852
2014	6.595
2015	6.019
2016	3.278
2017	10.778
2018	5.623
2019	-1.644
2020	1.361
2021	14.501
2022	6.557
2023	-7.039
2024	3.834
2025	3.711
2026	3.594
2027	3.612
2028	3.415
2029	3.151