Year	%
2000	36.6
2001	36.2
2002	36
2003	35.7
2004	35.5
2005	35.2
2006	35
2007	34.8
2008	34.5
2009	34.2
2010	34.1
2011	33.8
2012	33.6
2013	33.5
2014	33.4
2015	33.4
2016	33.3
2017	33.3
2018	33.3
2019	33.5