Year	%
2000	57.4
2001	57.4
2002	57.3
2003	57.2
2004	57
2005	56.9
2006	56.7
2007	56.4
2008	56.2
2009	55.9
2010	55.7
2011	55.3
2012	55
2013	54.6
2014	54.3
2015	54
2016	53.6
2017	53.2
2018	52.8
2019	52.5