Year	Percent change (Units)
1980	11.069
1981	14.973
1982	5.846
1983	1.366
1984	5.478
1985	-1.088
1986	5.934
1987	2.710
1988	2.891
1989	-10.661
1990	-1.604
1991	-5.650
1992	16.856
1993	4.360
1994	5.002
1995	5.951
1996	1.913
1997	3.741
1998	3.206
1999	3.237
2000	4.200
2001	4.987
2002	6.584
2003	3.980
2004	8.257
2005	8.822
2006	8.515
2007	8.373
2008	7.383
2009	5.024
2010	2.315
2011	2.737
2012	2.429
2013	2.610
2014	3.384
2015	2.497
2016	1.994
2017	2.474
2018	1.919
2019	1.751
2020	-1.103
2021	3.656
2022	2.428
2023	2.600
2024	2.600
2025	3.000
2026	3.000
2027	3.000
2028	3.000
2029	3.000