Year	Percent change (Units)
1980	3.299
1981	-4.542
1982	-11.557
1983	3.229
1984	2.419
1985	3.243
1986	6.104
1987	2.479
1988	0.054
1989	10.692
1990	9.310
1991	7.680
1992	-1.562
1993	3.561
1994	3.802
1995	2.997
1996	7.281
1997	4.797
1998	2.926
1999	6.245
2000	-0.061
2001	15.376
2002	3.106
2003	9.119
2004	1.560
2005	6.535
2006	4.662
2007	3.494
2008	4.773
2009	4.679
2010	5.413
2011	3.240
2012	-0.836
2013	2.295
2014	7.085
2015	6.172
2016	5.852
2017	5.305
2018	4.746
2019	4.765
2020	-1.244
2021	3.053
2022	3.475
2023	4.500
2024	4.000
2025	4.500
2026	4.900
2027	4.900
2028	4.900
2029	4.900