Year	Percent change (Units)
1991	8.302
1992	-7.170
1993	17.747
1994	-42.525
1995	34.843
1996	47.895
1997	11.093
1998	17.767
1999	-15.200
2000	-5.077
2001	13.705
2002	14.921
2003	2.472
2004	-9.854
2005	1.597
2006	7.573
2007	12.647
2008	7.872
2009	-3.808
2010	-4.506
2011	-12.388
2012	21.816
2013	-0.388
2014	2.029
2015	-8.436
2016	-5.110
2017	2.882
2018	8.949
2019	22.315
2020	17.171
2021	-8.570
2022	-7.689
2023	-3.821
2024	6.114
2025	0.810
2026	6.265
2027	5.774
2028	5.278
2029	4.782