Year	Percent change (Units)
1998	-42.991
1999	-37.471
2000	-26.014
2001	18.001
2002	-24.207
2003	119.100
2004	-74.696
2005	175.715
2006	-14.054
2007	4.189
2008	-20.731
2009	2.769
2010	2.233
2011	2366.057
2012	-1.147
2013	-63.851
2014	208.018
2015	-36.913
2016	-37.712
2017	74.868
2018	25.107
2019	29.801