Year	%
2004	18.5
2005	17.5
2006	18.3
2007	18.5
2008	18.2
2009	18.2
2010	18.2
2011	18.4
2012	18.7
2013	18.3
2014	19
2015	18.7
2016	19
2017	19.1
2018	18.8
2019	19
2020	19.1
2021	19.1