Year	%
2000	55.1
2001	55
2002	54.9
2003	54.8
2004	54.7
2005	54.6
2006	54.5
2007	54.2
2008	54
2009	53.8
2010	53.5
2011	53.3
2012	53
2013	52.9
2014	52.7
2015	52.6
2016	52.4
2017	52.1
2018	51.8
2019	51.5