Year	%
2000	22.5
2001	21.6
2002	21.4
2003	21.2
2004	20.4
2005	19.7
2006	19.1
2007	18.7
2008	18.3
2009	18.1
2010	17.8
2011	17.4
2012	16.9
2013	16.7
2014	15.7
2015	15.6
2016	15
2017	14.9
2018	14.8
2019	14.3