Year	%
2000	20.3
2001	19.8
2002	19.6
2003	18.8
2004	17.7
2005	17.7
2006	17.3
2007	16.7
2008	17
2009	16.2
2010	16.3
2011	15.8
2012	15.3
2013	14.8
2014	14.3
2015	14.2
2016	13.8
2017	13.6
2018	13.3
2019	13