Year	Percent change (Units)
1980	15.125
1981	10.432
1982	3.793
1983	8.827
1984	3.409
1985	4.976
1986	4.703
1987	4.681
1988	10.788
1989	5.485
1990	13.810
1991	12.659
1992	14.464
1993	9.630
1994	11.802
1995	12.079
1996	10.277
1997	12.454
1998	6.480
1999	3.684
2000	5.103
2001	2.535
2002	4.428
2003	1.919
2004	8.457
2005	8.736
2006	7.648
2007	6.997
2008	21.529
2009	10.964
2010	11.762
2011	13.313
2012	11.265
2013	5.853
2014	8.225
2015	3.158
2016	3.191
2017	3.932
2018	5.212
2019	8.000
2020	8.592
2021	9.699
2022	21.271
2023	29.401
2024	19.588
2025	9.488
2026	6.500
2027	6.493
2028	6.493
2029	6.493