Year	%
2003	36.6
2004	37.7
2005	38.5
2006	39.5
2007	38.9
2008	40.8
2009	38.1
2010	36
2011	36.2
2012	36.3
2013	35.3
2014	37.3
2015	36.5
2016	36.8
2017	35.9