Year	%
2000	19
2001	19.2
2002	18.5
2003	19.6
2004	20.2
2005	19.8
2006	18.4
2007	17.3
2008	16.9
2009	20.4
2010	19.9
2011	19.8
2012	18.8
2013	18.8
2014	18.9
2015	18.6
2016	19
2017	19
2018	19.4
2019	19.9