Year	%
2000	19.1
2001	18.3
2002	17.8
2003	17.8
2004	17.7
2005	17.4
2006	17.3
2007	17.2
2008	16.9
2009	16.7
2010	16.6
2011	16.5
2012	16.8
2013	16.2
2014	15.9
2015	16.2
2016	16.5
2017	16.2
2018	16.8
2019	16.8
