Year	%
2000	28
2001	28.2
2002	28.1
2003	28.2
2004	28.1
2005	28.7
2006	28.7
2007	28.2
2008	27.9
2009	27.7
2010	27.4
2011	27.2
2012	27
2013	26.7
2014	26.2
2015	25.5
2016	25
2017	24.4
2018	24.1
2019	23.9