Year	Percent change (Units)
1991	5.629
1992	10.142
1993	9.370
1994	4.128
1995	6.544
1996	4.681
1997	4.625
1998	8.032
1999	4.074
2000	3.254
2001	4.715
2002	3.896
2003	5.152
2004	10.368
2005	12.126
2006	6.241
2007	7.254
2008	7.450
2009	2.137
2010	6.262
2011	5.686
2012	4.902
2013	4.131
2014	3.772
2015	0.486
2016	1.472
2017	2.269
2018	3.053
2019	2.306
2020	2.382
2021	3.558
2022	9.553
2023	4.949
2024	2.785
2025	4.000
2026	4.000
2027	4.000
2028	4.000
2029	4.000