Year	%
2000	20.3
2001	20
2002	19.1
2003	19
2004	18.6
2005	18.5
2006	18.4
2007	17.7
2008	17.7
2009	17.2
2010	17
2011	16.5
2012	16.8
2013	16.9
2014	17.2
2015	17.3
2016	17.6
2017	17.8
2018	17.9
2019	17.7