Year	Percent
2006	32.1732
2007	31.2444
2008	30.27
2009	29.1403
2010	29.1663
2011	28.6454
2012	28.9936
2013	26.5914
2014	25.0549
2015	24.7764
2016	22.7187
2017	20.7567