Year	%
2004	28.2
2005	26.8
2006	26.4
2007	26.4
2008	26.1
2009	25.8
2010	25.8
2011	25.5
2012	25.3
2013	25.4
2014	25.2
2015	24.2
2016	24.6
2017	23.5
2018	24
2019	23.1
2020	22.8
2021	22.8