Year	%
2003	38.8
2004	38.9
2005	38.5
2006	38.1
2007	36.8
2008	36.6
2009	34.9
2010	35.8
2011	36.3
2012	36
2013	36.2
2014	35.6
2015	35.5
2016	35.2
2017	33.8
2018	33.5
2019	32.8
2020	34.7
2021	34.6