Year	%
2006	35.7
2007	36.1
2008	33.6
2009	33.8
2010	35.7
2011	34.3
2012	36
2013	36.6
2014	37.4
2015	38.6
2016	40.6
2017	40.4
2018	41.3
2019	40.3
2020	40.5
2021	39