Year	Percent change (Units)
1980	33.040
1981	26.450
1982	13.384
1983	7.452
1984	5.525
1985	8.321
1986	4.336
1987	0.719
1988	3.600
1989	13.610
1990	10.705
1991	12.817
1992	2.857
1993	15.288
1994	7.335
1995	6.026
1996	6.553
1997	6.831
1998	6.808
1999	6.882
2000	4.217
2001	5.391
2002	6.414
2003	2.686
2004	4.710
2005	4.937
2006	8.914
2007	8.825
2008	9.723
2009	2.524
2010	2.924
2011	6.532
2012	3.860
2013	3.535
2014	3.224
2015	1.275
2016	0.999
2017	3.675
2018	3.231
2019	0.454
2020	2.520
2021	4.039
2022	10.785
2023	7.045
2024	4.901
2025	3.574
2026	3.755
2027	3.519
2028	3.499
2029	3.516