Year	Percent change (Units)
1980	403.516
1981	47.845
1982	-6.045
1983	-10.257
1984	-6.678
1985	-18.302
1986	-10.141
1987	138.908
1988	-18.608
1989	4.148
1990	21.598
1991	-12.867
1992	30.114
1993	-15.005
1994	-18.645
1995	26.863
1996	-10.972
1997	2.217
1998	-7.287
1999	15.482
2000	4.282
2001	4.629
2002	16.885
2003	-13.726
2004	-4.356
2005	28.619
2006	-23.212
2007	10.232
2008	-2.001
2009	-4.027
2010	5.699
2011	25.726
2012	10.306
2013	4.045
2014	0.615
2015	-3.625
2016	5.235
2017	-1.218
2018	-15.893
2019	7.417
2020	-19.604
2021	24.022
2022	29.117
2023	-1.805
2024	5.712
2025	0.929
2026	3.093
2027	1.048
2028	1.733
2029	0.896