Year	%
2000	23.4
2001	22
2002	21.6
2003	20.4
2004	20.2
2005	19.3
2006	18.9
2007	18.3
2008	18.3
2009	17.9
2010	17.9
2011	17.8
2012	18
2013	18.1
2014	18.2
2015	18.3
2016	18.2
2017	18.4
2018	18.4
2019	18.3