Year	%
2000	24.7
2001	24.7
2002	24.7
2003	24.5
2004	24.1
2005	23.6
2006	23.1
2007	22.6
2008	22
2009	21.3
2010	20.6
2011	20.2
2012	20
2013	19.6
2014	19.3
2015	18.9
2016	18.6
2017	18.4
2018	18.2
2019	18.1