Year	%
2000	21.6
2001	21.1
2002	20.5
2003	20.1
2004	20
2005	19
2006	18.7
2007	18.4
2008	18.4
2009	18
2010	17.7
2011	17.6
2012	17.1
2013	16.8
2014	16.3
2015	16.2
2016	16.3
2017	15.8
2018	15.7
2019	15.5