Year	Percent change (Units)
1980	41.493
1981	-8.239
1982	-42.580
1983	-6.924
1984	4.705
1985	-13.038
1986	18.523
1987	11.422
1988	-9.204
1989	-16.419
1990	-0.690
1991	75.576
1992	66.462
1993	13.423
1994	26.700
1995	-11.484
1996	19.483
1997	29.985
1998	9.894
1999	-15.929
2000	-2.322
2001	-16.587
2002	-53.558
2003	48.953
2004	51.050
2005	18.243
2006	12.871
2007	22.147
2008	14.525
2009	-23.812
2010	39.539
2011	21.710
2012	-5.815
2013	3.576
2014	-10.942
2015	2.717
2016	3.499
2017	14.346
2018	-6.082
2019	-20.997
2020	-10.411
2021	29.637
2022	12.839
2023	6.148
2024	-15.151
2025	6.732
2026	5.314
2027	4.904
2028	4.182
2029	3.295