Year	%
2000	51.2
2001	51.1
2002	51.1
2003	51
2004	50.9
2005	50.8
2006	50.7
2007	50.5
2008	50.3
2009	50.1
2010	49.9
2011	49.7
2012	49.5
2013	49.4
2014	49.3
2015	49.2
2016	49.1
2017	49
2018	48.8
2019	48.7