Year	Percent change (Units)
1980	-15.614
1981	0.225
1982	45.337
1983	21.728
1984	10.149
1985	25.437
1986	19.391
1987	3.084
1988	-27.444
1989	29.674
1990	36.490
1991	71.417
1992	35.017
1993	19.604
1994	38.545
1995	22.229
1996	6.796
1997	15.616
1998	-2.770
1999	7.933
2000	-5.970
2001	4.006
2002	10.187
2003	19.167
2004	29.593
2005	5.950
2006	14.301
2007	13.309
2008	2.128
2009	5.386
2010	6.577
2011	8.476
2012	14.429
2013	18.093
2014	11.510
2015	14.835
2016	11.941
2017	16.719
2018	12.061
2019	6.225
2020	2.792
2021	13.634
2022	6.401
2023	-3.901
2024	4.660
2025	5.492
2026	7.153
2027	7.115
2028	6.871
2029	6.897