Year	%
2000	35.2
2001	34.8
2002	34.5
2003	34.3
2004	34.1
2005	33.9
2006	33.7
2007	33.6
2008	33.6
2009	33.4
2010	33.2
2011	33
2012	32.8
2013	32.6
2014	32.5
2015	32.4
2016	32.3
2017	32.2
2018	32.2
2019	32.2