Year	%
2004	39
2005	39.3
2006	40.1
2007	40
2008	40.6
2009	40.8
2010	40.4
2011	41.3
2012	42.7
2013	45.1
2014	43.6
2015	42.1
2016	41.4
2017	40.2
2018	41.4
2019	40.1
2020	40.6
2021	40.1