Year	Percent change (Units)
1980	17.452
1981	12.108
1982	8.578
1983	8.907
1984	8.021
1985	7.367
1986	4.233
1987	4.222
1988	5.798
1989	6.437
1990	10.470
1991	8.792
1992	1.378
1993	4.689
1994	2.910
1995	2.465
1996	1.020
1997	1.818
1998	1.008
1999	0.570
2000	1.295
2001	2.681
2002	1.936
2003	2.318
2004	1.019
2005	0.835
2006	1.500
2007	1.679
2008	3.347
2009	1.938
2010	1.900
2011	1.360
2012	0.937
2013	0.442
2014	0.209
2015	0.703
2016	1.140
2017	1.868
2018	2.035
2019	1.720
2020	0.658
2021	2.651
2022	8.055
2023	5.910
2024	2.574
2025	1.987
2026	2.000
2027	2.000
2028	2.000
2029	2.000