Year	Percent change (Units)
1991	1.570
1992	-3.038
1993	14.232
1994	60.353
1995	7.486
1996	0.210
1997	16.440
1998	-2.915
1999	18.366
2000	-1.193
2001	1.533
2002	8.999
2003	-6.018
2004	-9.004
2005	-2.029
2006	-3.882
2007	-10.774
2008	-2.027
2009	1.712
2010	6.237
2011	-17.081
2012	-11.694
2013	2.853
2014	5.812
2015	-50.395
2016	-51.725
2017	28.158
2018	-19.070
2019	5.494
2020	11.223
2021	0.931
2022	-25.942
2023	-51.701
2024	-0.585
2025	9.018
2026	242.030
2027	136.919
2028	13.040
2029	12.164