Year	Percent change (Units)
1980	10.671
1981	12.397
1982	8.824
1983	6.081
1984	5.732
1985	3.414
1986	4.466
1987	3.903
1988	4.651
1989	4.786
1990	1.794
1991	2.157
1992	1.207
1993	1.043
1994	2.507
1995	1.727
1996	2.263
1997	1.521
1998	1.226
1999	3.096
2000	2.350
2001	2.041
2002	2.625
2003	1.218
2004	0.963
2005	2.265
2006	1.632
2007	2.523
2008	2.461
2009	1.201
2010	2.805
2011	2.413
2012	1.742
2013	0.504
2014	0.000
2015	0.301
2016	0.300
2017	0.896
2018	0.790
2019	0.881
2020	0.485
2021	3.478
2022	9.711
2023	0.511
2024	1.877
2025	1.893
2026	2.000
2027	2.000
2028	2.000
2029	2.000