Year	Percent
2004	3.36
2005	4.12
2006	3.57
2007	3.07
2008	4.07
2009	4.49
2010	4.29
2011	4.47
2012	4.2
2013	3.81
2014	4.4
2015	4.41
2016	4.22
2017	2.97