Year	Percent change (Units)
1980	-44.338
1981	48.945
1982	11.543
1983	-11.398
1984	9.921
1985	12.600
1986	-12.629
1987	8.917
1988	1.766
1989	-10.015
1990	0.413
1991	22.903
1992	5.976
1993	-19.221
1994	-20.668
1995	28.289
1996	-49.669
1997	64.512
1998	-23.443
1999	5.611
2000	5.901
2001	8.967
2002	-14.017
2003	38.555
2004	-11.685
2005	24.653
2006	-20.639
2007	21.323
2008	16.101
2009	-20.627
2010	16.901
2011	5.532
2012	2.205
2013	37.327
2014	-12.715
2015	-7.099
2016	27.722
2017	29.970
2018	13.224
2019	-15.813
2020	-15.366
2021	5.135
2022	-2.178
2023	15.645
2024	14.779
2025	7.727
2026	20.929
2027	24.986
2028	11.200
2029	10.576