Year	Percent change (Units)
1980	10.587
1981	-2.674
1982	13.893
1983	-7.524
1984	12.935
1985	-8.029
1986	29.929
1987	32.692
1988	2.981
1989	4.685
1990	-4.044
1991	-4.044
1992	-4.044
1993	-4.044
1994	8.016
1995	3.980
1996	18.471
1997	19.472
1998	18.833
1999	18.223
2000	31.491
2001	10.606
2002	13.467
2003	1.730
2004	-2.636
2005	-1.097
2006	-1.243
2007	-3.957
2008	-0.253
2009	-19.508
2010	7.977
2011	5.064
2012	7.861
2013	8.790
2014	8.964
2015	-6.856
2016	-13.533
2017	-1.492
2018	0.871
2019	-5.067
2020	-16.756
2021	-1.593
2022	9.687
2023	-1.109
2024	9.059
2025	9.961
2026	6.181
2027	4.096
2028	2.218
2029	2.265