Year	%
2000	20.2
2001	20.7
2002	19.3
2003	20.3
2004	19.5
2005	19.4
2006	19.1
2007	19.6
2008	19.6
2009	19.6
2010	19.5
2011	19.9
2012	19.7
2013	19.4
2014	19.7
2015	19.2
2016	19.1
2017	18.7
2018	17.8
2019	16.9