Year	Percent change (Units)
1980	316.595
1981	116.809
1982	120.365
1983	145.638
1984	373.820
1985	304.584
1986	48.155
1987	19.853
1988	16.231
1989	20.249
1990	17.173
1991	19.006
1992	11.948
1993	10.944
1994	12.342
1995	10.043
1996	11.277
1997	9.001
1998	5.435
1999	5.194
2000	1.125
2001	1.116
2002	5.687
2003	0.670
2004	-0.414
2005	1.329
2006	2.107
2007	0.516
2008	4.594
2009	3.317
2010	2.694
2011	3.450
2012	1.708
2013	1.526
2014	0.476
2015	-0.632
2016	-0.545
2017	0.242
2018	0.807
2019	0.842
2020	-0.587
2021	1.492
2022	4.395
2023	4.208
2024	2.448
2025	2.547
2026	2.121
2027	2.092
2028	2.040
2029	1.998