Year	%
2000	19.3
2001	18.8
2002	18.5
2003	18.3
2004	17.7
2005	17.5
2006	16.9
2007	16.5
2008	16
2009	15.9
2010	15.4
2011	15.1
2012	14.8
2013	14.3
2014	14
2015	14
2016	13.9
2017	13.6
2018	13.1
2019	12.8