Year	%
2000	38.6
2001	38.6
2002	38.5
2003	38.4
2004	38.3
2005	38.3
2006	38.2
2007	38.1
2008	37.9
2009	37.7
2010	37.5
2011	37.3
2012	37.1
2013	37
2014	36.9
2015	36.9
2016	36.8
2017	36.7
2018	36.6
2019	36.5