Year	%
2000	17.4
2001	17
2002	16.5
2003	16.2
2004	15.9
2005	15.7
2006	15.5
2007	14.6
2008	14.3
2009	13.9
2010	13.7
2011	13.6
2012	13.8
2013	13.9
2014	14
2015	14.1
2016	14.6
2017	14.7
2018	14.7
2019	14.6