Year	Percent change (Units)
1980	7.681
1981	7.546
1982	15.326
1983	20.509
1984	12.095
1985	4.202
1986	4.301
1987	2.794
1988	1.705
1989	1.597
1990	1.504
1991	-0.602
1992	1.886
1993	-3.720
1994	14.880
1995	25.805
1996	3.921
1997	4.783
1998	3.177
1999	1.832
2000	1.245
2001	4.450
2002	2.817
2003	0.630
2004	0.250
2005	1.993
2006	4.906
2007	1.125
2008	5.338
2009	3.040
2010	1.279
2011	2.955
2012	2.384
2013	2.050
2014	1.855
2015	2.678
2016	0.873
2017	0.641
2018	1.064
2019	2.456
2020	2.451
2021	2.262
2022	6.252
2023	7.191
2024	5.900
2025	5.500
2026	4.900
2027	3.400
2028	2.500
2029	2.500