Year	%
2000	22.9
2001	22.3
2002	22
2003	21.9
2004	20.6
2005	20.7
2006	19.8
2007	19.9
2008	20.1
2009	19.5
2010	18.8
2011	18.3
2012	17.8
2013	17
2014	17
2015	17.6
2016	17
2017	16.8
2018	16.3
2019	16.1