Year	Percent change (Units)
1980	4.956
1981	-9.582
1982	9.886
1983	17.309
1984	12.141
1985	-2.720
1986	11.787
1987	14.557
1988	11.803
1989	18.112
1990	16.900
1991	14.362
1992	12.547
1993	11.810
1994	21.518
1995	18.552
1996	8.995
1997	5.279
1998	-0.261
1999	13.664
2000	13.278
2001	-2.658
2002	7.241
2003	7.407
2004	21.797
2005	5.778
2006	6.907
2007	-3.852
2008	-13.055
2009	-10.467
2010	3.622
2011	6.257
2012	-6.492
2013	0.074
2014	6.502
2015	4.050
2016	3.890
2017	7.260
2018	2.125
2019	-0.812
2020	0.401
2021	17.419
2022	9.075
2023	-4.721
2024	4.156
2025	5.770
2026	3.632
2027	4.076
2028	4.486
2029	4.446