Year	Percent
2001	36
2002	33
2003	24.7
2004	23.4
2005	20.2
2006	13.6
2007	6.9
2008	8.1
2009	4.1
2010	3.7
2011	2.4
2012	1.9
2013	1.3
2014	1.3
2015	1.3