Year	%
2000	25.3
2001	25
2002	24.5
2003	24.1
2004	24.1
2005	24.2
2006	23.5
2007	21.8
2008	20.5
2009	20.2
2010	19.7
2011	19.5
2012	18.7
2013	18.6
2014	18.6
2015	18.5
2016	18.8
2017	18.3
2018	18.2
2019	18.3