Year	%
2000	17.7
2001	16.8
2002	16.9
2003	16
2004	16.5
2005	16.1
2006	16.7
2007	17.1
2008	17.1
2009	17.6
2010	17.9
2011	18.5
2012	18.1
2013	17.4
2014	17.1
2015	15.4
2016	15.3
2017	15.2
2018	15
2019	15.4