Year	%
2000	38.7
2001	38.6
2002	38.5
2003	38.4
2004	38.3
2005	38
2006	37.5
2007	36.8
2008	36.3
2009	35.8
2010	35.5
2011	35.3
2012	35.2
2013	35.2
2014	35.2
2015	35.2
2016	35.1
2017	35.1
2018	35.1
2019	35