Year	Percent change (Units)
1980	9.046
1981	-0.261
1982	-17.133
1983	13.414
1984	2.003
1985	11.277
1986	10.142
1987	4.360
1988	-1.210
1989	3.521
1990	-1.400
1991	-7.901
1992	-1.021
1993	5.080
1994	12.161
1995	-2.220
1996	9.119
1997	5.847
1998	-3.155
1999	4.697
2000	-2.463
2001	4.450
2002	7.419
2003	-1.247
2004	9.737
2005	-1.613
2006	-5.419
2007	17.522
2008	11.877
2009	9.059
2010	-4.476
2011	2.695
2012	3.440
2013	3.768
2014	2.758
2015	3.186
2016	3.720
2017	1.092
2018	3.852
2019	-0.713
2020	-7.157
2021	7.276
2022	1.539
2023	1.057
2024	2.181
2025	3.066
2026	3.273
2027	3.175
2028	3.175
2029	3.175