Year	%
2004	17
2005	16.9
2006	16.7
2007	16.7
2008	16.6
2009	16.4
2010	16.4
2011	16.2
2012	15.8
2013	15.1
2014	15.8
2015	16.2
2016	16.3
2017	16.7
2018	16.2
2019	16.7
2020	16.5
2021	16.8