Year	%
2000	34.7
2001	34.4
2002	34.1
2003	33.9
2004	33.6
2005	33.3
2006	32.9
2007	32.4
2008	32
2009	31.7
2010	31.4
2011	31.1
2012	31
2013	31
2014	31
2015	31.2
2016	31.3
2017	31.4
2018	31.4
2019	31.4