Year	%
2000	19.2
2001	18.8
2002	18.5
2003	18.3
2004	18.1
2005	18
2006	17.9
2007	17.8
2008	17.7
2009	17.6
2010	17.6
2011	17.6
2012	17.7
2013	17.7
2014	17.8
2015	18
2016	18.1
2017	18.3
2018	18.4
2019	18.5