Year	%
2000	51.5
2001	51.6
2002	51.6
2003	51.6
2004	51.5
2005	51.5
2006	51.4
2007	51.3
2008	51.1
2009	50.9
2010	50.8
2011	50.6
2012	50.5
2013	50.4
2014	50.2
2015	50.1
2016	49.9
2017	49.7
2018	49.5
2019	49.3