Year	Percent change (Units)
1980	21.821
1981	18.787
1982	7.813
1983	6.095
1984	5.660
1985	2.501
1986	0.557
1987	-0.872
1988	4.000
1989	5.593
1990	2.724
1991	2.645
1992	3.778
1993	2.809
1994	6.435
1995	3.027
1996	2.032
1997	1.245
1998	1.405
1999	0.574
2000	2.142
2001	1.671
2002	1.067
2003	2.155
2004	2.313
2005	3.476
2006	4.252
2007	3.859
2008	8.033
2009	-0.309
2010	3.437
2011	3.033
2012	2.411
2013	-0.044
2014	-0.983
2015	-0.584
2016	1.716
2017	0.911
2018	0.805
2019	0.599
2020	-0.742
2021	1.220
2022	2.582
2023	3.037
2024	1.709
2025	2.018
2026	2.024
2027	2.024
2028	2.024
2029	2.024