Year	%
2004	22.2
2005	22
2006	22.1
2007	22.4
2008	22.1
2009	22.7
2010	23.2
2011	23
2012	22.6
2013	22.4
2014	22.3
2015	22.1
2016	21.8
2017	22.3
2018	22.4
2019	22.1
2020	21.5
2021	21.7