Year	%
2000	56.5
2001	56.4
2002	56.4
2003	56.3
2004	56.2
2005	56
2006	55.8
2007	55.5
2008	55.2
2009	54.8
2010	54.5
2011	54.1
2012	53.7
2013	53.3
2014	52.9
2015	52.6
2016	52.2
2017	51.7
2018	51.3
2019	51