Year	%
2000	21.2
2001	20.6
2002	20.2
2003	20
2004	18.9
2005	19.1
2006	18.5
2007	17.8
2008	17.6
2009	17.2
2010	17.2
2011	16.9
2012	16.7
2013	16.5
2014	15.9
2015	16
2016	16
2017	15.7
2018	16
2019	15.4