Year	%
2000	20.2
2001	19.6
2002	19.1
2003	19.2
2004	19
2005	18.5
2006	18.5
2007	18
2008	19.1
2009	18.6
2010	17.4
2011	16.3
2012	16.2
2013	15.3
2014	14.8
2015	15.3
2016	14.4
2017	14.1
2018	13.4
2019	13.4