Year	%
2000	18.7
2001	18.3
2002	18
2003	17.8
2004	17.6
2005	17.4
2006	17.3
2007	17.2
2008	17.1
2009	17
2010	16.9
2011	16.9
2012	17
2013	17
2014	17.1
2015	17.3
2016	17.4
2017	17.6
2018	17.8
2019	18