Year	Percent
2003	20.1
2004	20.1
2005	20.3
2006	19.7
2007	19.8
2008	20.4
2009	20.7
2010	20.6
2011	20.8
2012	20.4
2013	22.2
2014	22.1
2015	22.3
2016	21.6
2017	21.5
2018	20.7
2019	21
2020	21.7
2021	20.4