Year	Percent
1996	24.9
2001	32.5
2002	28.1
2003	23
2004	16.7
2005	24.3
2006	6
2007	3
2008	2.2
2009	2.6
2010	1.9
2011	0.7
2012	0.4
2013	0.3
2014	0.2
2015	0.3