Year	%
2000	20.2
2001	18.3
2002	17.9
2003	17.4
2004	17.4
2005	16.8
2006	16.4
2007	15.7
2008	15.3
2009	14.9
2010	14.9
2011	14.6
2012	14.3
2013	13.9
2014	13.9
2015	13.8
2016	14
2017	13.8
2018	13.8
2019	13.7