Year	%
2000	28.1
2001	27.9
2002	27.7
2003	27.4
2004	27.1
2005	26.6
2006	26.1
2007	25.6
2008	25
2009	24.4
2010	24
2011	23.8
2012	23.7
2013	23.6
2014	23.6
2015	23.6
2016	23.7
2017	23.8
2018	23.9
2019	23.9