Year	Percent
2004	13.3
2005	11.6
2006	10.6
2007	10.9
2008	11
2009	12
2010	13
2011	13.2
2012	12.8
2013	12.6
2014	12.3
2015	12.7
2016	12.4
2017	12.2
2018	11.9
2019	11.4
2020	12.3
2021	13.7