Year	%
2000	38
2001	37.6
2002	37.2
2003	37
2004	36.7
2005	36.4
2006	36.1
2007	35.7
2008	35.3
2009	35
2010	34.7
2011	34.6
2012	34.6
2013	34.5
2014	34.3
2015	34.1
2016	34
2017	33.9
2018	33.7
2019	33.5