Year	%
2000	17.8
2001	17.5
2002	17.8
2003	18
2004	17.8
2005	16.9
2006	16
2007	15.3
2008	14.7
2009	14.2
2010	13.8
2011	13.4
2012	12.8
2013	12.3
2014	12
2015	11.7
2016	11.5
2017	11.4
2018	11.3
2019	11.2