Year	%
2000	21.7
2001	22.3
2002	22.1
2003	21.8
2004	21.7
2005	21.5
2006	21.2
2007	20.9
2008	20.9
2009	20.8
2010	20.6
2011	20.6
2012	20.6
2013	20.7
2014	20.8
2015	20.6
2016	20.5
2017	20.2
2018	20
2019	19.9