Year	%
2000	23.9
2001	23.3
2002	23.2
2003	23.3
2004	23.4
2005	23.8
2006	22.7
2007	22.5
2008	22.1
2009	20.6
2010	19.9
2011	18.8
2012	18.5
2013	17.9
2014	18
2015	16.8
2016	16.6
2017	16
2018	16.4
2019	16