Year	%
2004	28.5
2005	30
2006	26.8
2007	28.3
2008	27.7
2009	26.9
2010	26.2
2011	27.3
2012	26.6
2013	26.8
2014	26.7
2015	26.2
2016	25.8
2017	26.9
2018	26.9
2019	26.6
2020	27.5
2021	26.2