Year	Percent change (Units)
1980	7.195
1981	6.438
1982	12.613
1983	6.629
1984	5.359
1985	1.729
1986	-1.100
1987	4.146
1988	2.913
1989	1.038
1990	4.202
1991	19.600
1992	9.500
1993	12.468
1994	20.996
1995	55.967
1996	13.193
1997	11.755
1998	6.462
1999	-2.419
2000	3.908
2001	3.359
2002	1.981
2003	7.445
2004	11.980
2005	9.122
2006	8.831
2007	9.081
2008	15.440
2009	10.343
2010	2.319
2011	5.664
2012	6.285
2013	4.218
2014	1.771
2015	2.535
2016	5.720
2017	4.823
2018	1.355
2019	2.417
2020	7.733
2021	0.828
2022	13.882
2023	14.029
2024	5.800
2025	5.000
2026	5.000
2027	5.000
2028	5.000
2029	5.000