Year	Percent change (Units)
1997	8.897
1998	9.700
1999	2.466
2000	0.564
2001	1.848
2002	6.416
2003	3.791
2004	3.917
2005	4.574
2006	3.186
2007	4.814
2008	6.952
2009	4.341
2010	2.818
2011	2.752
2012	1.726
2013	2.706
2014	1.196
2015	0.961
2016	-1.041
2017	-0.020
2018	0.321
2019	1.269
2020	0.069
2021	1.302
2022	4.088
2023	15.233