Year	Percent change (Units)
1980	12.504
1981	4.967
1982	9.918
1983	12.137
1984	13.046
1985	8.001
1986	5.177
1987	7.044
1988	8.183
1989	8.864
1990	9.408
1991	10.345
1992	8.144
1993	9.595
1994	9.497
1995	7.084
1996	8.779
1997	8.551
1998	7.591
1999	9.058
2000	7.183
2001	3.724
2002	2.939
2003	2.472
2004	3.346
2005	4.823
2006	4.930
2007	5.246
2008	6.300
2009	7.127
2010	4.826
2011	8.552
2012	10.115
2013	8.109
2014	9.599
2015	6.650
2016	3.268
2017	4.325
2018	3.661
2019	2.813
2020	3.048
2021	8.211
2022	5.935
2023	4.555
2024	4.898
2025	4.586
2026	4.086
2027	4.003
2028	3.960
2029	3.960