Year	%
2004	35.9
2005	38.3
2006	35.5
2007	34.5
2008	35.6
2009	36.1
2010	36.1
2011	35.4
2012	34.9
2013	36.5
2014	34.5
2015	35
2016	34
2017	32.6
2018	33.8
2019	32.8
2020	33.3
2021	33.3