Year	Percent change (Units)
1980	10.631
1981	3.000
1982	-7.800
1983	0.000
1984	1.500
1985	-2.500
1986	-4.500
1987	-7.500
1988	3.800
1989	26.500
1990	-8.200
1991	-4.300
1992	8.600
1993	2.600
1994	22.700
1995	17.100
1996	-6.600
1997	12.269
1998	10.949
1999	21.133
2000	-6.664
2001	13.172
2002	23.366
2003	21.852
2004	13.115
2005	-5.064
2006	22.145
2007	22.473
2008	11.749
2009	-9.790
2010	0.466
2011	12.947
2012	-13.068
2013	-2.538
2014	10.425
2015	-22.606
2016	19.319
2017	13.873
2018	5.589
2019	1.360
2020	-17.474
2021	-4.074
2022	5.839
2023	16.712
2024	9.297
2025	5.521
2026	4.550
2027	4.358
2028	3.172
2029	3.829