Year	Percent
2005	3.1926
2006	2.8342
2007	2.1702
2008	2.4608
2009	2.3176
2010	2.5618
2011	2.8852
2012	2.5746
2013	3.1593
2014	3.7417
2015	3.2832
2016	3.4297
2017	2.2912