Year	%
2000	57.6
2001	57.5
2002	57.4
2003	57.3
2004	57.2
2005	57.1
2006	57
2007	56.8
2008	56.6
2009	56.5
2010	56.3
2011	56.1
2012	56
2013	55.8
2014	55.6
2015	55.4
2016	55.2
2017	55
2018	54.7
2019	54.4