Year	%
2000	18.8
2001	18.4
2002	18
2003	17.1
2004	16.7
2005	15.5
2006	15.2
2007	15.2
2008	14.4
2009	13.9
2010	13.7
2011	13.5
2012	13.3
2013	12.7
2014	12.6
2015	12.6
2016	12.5
2017	12.8
2018	12.2
2019	12.1