Year	%
2000	19.4
2001	18.4
2002	18.9
2003	18.8
2004	19.2
2005	19.1
2006	18.9
2007	18.6
2008	18.1
2009	17.4
2010	17.1
2011	16.7
2012	16.3
2013	16.6
2014	16.8
2015	16.6
2016	16.8
2017	16.8
2018	17
2019	17.5