Year	%
2006	29
2007	27.4
2008	26.5
2009	25.7
2010	25
2011	24.9
2012	25.5
2013	25.4
2014	24.5
2015	24.8
2016	23.7
2017	24.9
2018	24.9
2019	24.5
2020	24.2
2021	24