Year	%
2000	21.7
2001	22.5
2002	23
2003	22
2004	21.3
2005	21.3
2006	20.2
2007	19
2008	18.8
2009	18.5
2010	18.4
2011	18.2
2012	16.4
2013	15.8
2014	15.2
2015	14.4
2016	14.4
2017	14
2018	14
2019	13.6