Year	Percent change (Units)
1980	0.606
1981	-20.040
1982	1.518
1983	-4.709
1984	-8.306
1985	0.607
1986	-11.353
1987	-14.702
1988	7.579
1989	7.199
1990	3.720
1991	18.320
1992	-4.545
1993	-5.468
1994	3.219
1995	-15.431
1996	1.759
1997	-2.635
1998	-0.676
1999	-0.189
2000	4.042
2001	2.626
2002	-3.727
2003	16.145
2004	5.845
2005	10.619
2006	0.278
2007	6.230
2008	-0.162
2009	-4.400
2010	5.027
2011	-50.339
2012	86.827
2013	-17.998
2014	-23.043
2015	-0.843
2016	-1.491
2017	32.492
2018	7.941
2019	-11.196
2020	-29.456
2021	28.335
2022	-8.252
2023	10.156
2024	7.832
2025	6.946
2026	4.174
2027	2.007
2028	2.147
2029	2.295