Year	Percent change (Units)
1980	4.500
1981	9.207
1982	5.348
1983	-4.491
1984	2.709
1985	4.942
1986	3.568
1987	-1.809
1988	-13.380
1989	1.562
1990	8.099
1991	9.418
1992	8.203
1993	5.456
1994	2.849
1995	1.752
1996	7.371
1997	6.480
1998	7.332
1999	3.878
2000	2.737
2001	0.558
2002	2.247
2003	4.226
2004	7.508
2005	7.181
2006	8.541
2007	12.111
2008	9.856
2009	1.243
2010	5.828
2011	11.314
2012	9.779
2013	6.903
2014	5.067
2015	5.733
2016	4.953
2017	5.591
2018	3.685
2019	3.282
2020	-17.668
2021	15.836
2022	10.809
2023	7.317
2024	2.500
2025	3.000
2026	4.000
2027	4.000
2028	4.000
2029	4.000