Year	%
2000	51.8
2001	51.8
2002	51.8
2003	51.8
2004	51.7
2005	51.5
2006	51.3
2007	51
2008	50.7
2009	50.3
2010	49.9
2011	49.5
2012	49.1
2013	48.7
2014	48.3
2015	47.8
2016	47.3
2017	46.8
2018	46.3
2019	45.8