Year	%
2004	30.1
2005	30.3
2006	31.1
2007	31.1
2008	31.7
2009	32.1
2010	31.5
2011	32.6
2012	34.3
2013	37
2014	35.6
2015	34
2016	32.9
2017	31.4
2018	32.7
2019	31.2
2020	31.7
2021	31.3