Year	%
2000	16.9
2001	16.6
2002	16.3
2003	16.1
2004	15.9
2005	15.7
2006	15.5
2007	15.4
2008	15.3
2009	15.2
2010	15.2
2011	15.2
2012	15.3
2013	15.4
2014	15.5
2015	15.6
2016	15.8
2017	16
2018	16.1
2019	16.3