Year	%
2000	59.1
2001	59.1
2002	58.9
2003	58.8
2004	58.6
2005	58.4
2006	58.2
2007	58
2008	57.7
2009	57.5
2010	57.3
2011	57.1
2012	56.9
2013	56.8
2014	56.6
2015	56.5
2016	56.3
2017	56.2
2018	56
2019	55.9