Year	Percent change (Units)
1980	14.074
1981	9.131
1982	8.880
1983	8.834
1984	7.586
1985	6.429
1986	3.631
1987	5.253
1988	5.907
1989	6.511
1990	11.172
1991	7.837
1992	0.532
1993	5.124
1994	2.637
1995	2.313
1996	0.474
1997	2.639
1998	0.068
1999	0.974
2000	1.504
2001	3.038
2002	1.595
2003	1.911
2004	1.128
2005	1.104
2006	1.404
2007	2.292
2008	2.665
2009	2.327
2010	1.777
2011	0.835
2012	0.973
2013	0.253
2014	0.309
2015	0.851
2016	1.416
2017	1.776
2018	2.218
2019	1.710
2020	0.399
2021	3.904
2022	10.231
2023	3.024
2024	2.350
2025	2.000
2026	2.000
2027	2.000
2028	2.000
2029	2.000