Year	%
2003	17.6
2004	17.2
2005	17.1
2006	16.7
2007	16.8
2008	16.4
2009	17.3
2010	17.9
2011	18
2012	17.8
2013	17.9
2014	17.6
2015	17.7
2016	17.5
2017	17.9