Year	%
2000	17.9
2001	17.6
2002	17.4
2003	17.3
2004	17.2
2005	17.1
2006	17
2007	16.9
2008	16.9
2009	16.9
2010	16.8
2011	16.9
2012	16.9
2013	17
2014	17.1
2015	17.3
2016	17.4
2017	17.6
2018	17.7
2019	17.8