Year	%
2003	22.6
2004	23.7
2005	24.4
2006	25.4
2007	24.8
2008	27.1
2009	24
2010	22
2011	22.1
2012	22.1
2013	21.3
2014	23.5
2015	22.5
2016	22.8
2017	22.1