Year	%
2000	20.2
2001	19.6
2002	19.5
2003	19.1
2004	18.7
2005	18.6
2006	18.5
2007	17.7
2008	17.2
2009	17.1
2010	17
2011	16.6
2012	16.2
2013	15.4
2014	16.5
2015	16.1
2016	16.3
2017	16.4
2018	16.4
2019	16.4