Year	Percent change (Units)
1991	3.606
1992	17.562
1993	1.493
1994	2.699
1995	9.001
1996	4.479
1997	5.533
1998	8.250
1999	1.927
2000	5.578
2001	1.732
2002	8.402
2003	2.398
2004	16.144
2005	5.805
2006	8.887
2007	7.410
2008	3.906
2009	4.915
2010	6.143
2011	5.472
2012	3.405
2013	4.486
2014	5.001
2015	-2.830
2016	2.770
2017	1.236
2018	3.154
2019	2.702
2020	1.826
2021	5.707
2022	11.014
2023	1.569
2024	4.000
2025	4.000
2026	4.000
2027	4.000
2028	4.000
2029	4.000