Year	Percent change (Units)
1991	13.512
1992	21.551
1993	9.329
1994	12.056
1995	11.123
1996	8.704
1997	9.679
1998	6.617
1999	9.382
2000	10.215
2001	10.212
2002	12.716
2003	7.215
2004	4.137
2005	2.282
2006	4.961
2007	6.548
2008	9.095
2009	9.452
2010	4.875
2011	5.006
2012	6.722
2013	5.601
2014	5.348
2015	3.396
2016	6.727
2017	6.147
2018	4.294
2019	3.721
2020	2.209
2021	3.620
2022	6.077
2023	5.880
2024	4.811
2025	4.811
2026	4.811
2027	4.811
2028	4.811
2029	4.811