Year	%
2000	28.4
2001	28.1
2002	27.9
2003	27.6
2004	27.3
2005	27
2006	26.7
2007	26.4
2008	26.1
2009	25.8
2010	25.5
2011	25.3
2012	25.2
2013	25
2014	24.9
2015	24.8
2016	24.9
2017	25
2018	25.1
2019	25.1