Year	Percent change (Units)
1980	3.854
1981	6.631
1982	-2.912
1983	-1.145
1984	-1.718
1985	1.237
1986	1.698
1987	1.491
1988	9.271
1989	-3.658
1990	-0.579
1991	-0.666
1992	2.052
1993	-0.077
1994	-13.309
1995	2.898
1996	6.219
1997	3.814
1998	-0.386
1999	4.650
2000	3.897
2001	5.317
2002	4.506
2003	6.945
2004	7.032
2005	7.236
2006	7.904
2007	8.352
2008	7.774
2009	9.220
2010	10.298
2011	5.565
2012	7.598
2013	5.057
2014	4.698
2015	2.920
2016	3.777
2017	3.504
2018	4.035
2019	1.441
2020	-2.785
2021	6.235
2022	5.250
2023	4.330
2024	4.715
2025	4.847
2026	4.771
2027	4.930
2028	4.978
2029	4.924