Year	Percent change (Units)
1980	10.136
1981	9.488
1982	11.352
1983	10.039
1984	3.960
1985	6.735
1986	9.050
1987	8.533
1988	7.270
1989	7.580
1990	7.233
1991	3.307
1992	0.969
1993	1.752
1994	1.927
1995	4.626
1996	2.653
1997	0.225
1998	0.859
1999	1.408
2000	4.457
2001	4.407
2002	3.049
2003	2.731
2004	2.342
2005	2.659
2006	3.554
2007	2.356
2008	4.348
2009	1.770
2010	2.863
2011	3.356
2012	1.686
2013	2.450
2014	2.513
2015	1.485
2016	1.277
2017	1.995
2018	1.911
2019	1.588
2020	0.912
2021	2.819
2022	6.614
2023	5.595
2024	3.530
2025	2.982
2026	2.676
2027	2.677
2028	2.574
2029	2.499