Year	%
2000	21
2001	20.6
2002	20.2
2003	19.9
2004	19.6
2005	19.4
2006	19.2
2007	19
2008	18.8
2009	18.7
2010	18.7
2011	18.6
2012	18.5
2013	18.6
2014	18.5
2015	18.6
2016	18.6
2017	18.7
2018	18.9
2019	19