Year	Percent change (Units)
1991	2.737
1992	1.047
1993	0.235
1994	-0.892
1995	-0.322
1996	0.067
1997	0.034
1998	0.470
1999	-0.345
2000	-1.020
2001	-4.142
2002	-0.101
2003	-0.101
2004	2.018
2005	1.879
2006	4.272
2007	8.287
2008	11.780
2009	0.923
2010	4.192
2011	3.292
2012	4.377
2013	0.784
2014	1.003
2015	-0.024
2016	0.739
2017	1.667
2018	0.568
2019	0.489
2020	-0.884
2021	3.601
2022	1.497
2023	0.642
2024	1.004
2025	1.500
2026	2.000
2027	2.000
2028	2.000
2029	2.000