Year	%
2000	33.3
2001	32.7
2002	33.4
2003	34.1
2004	33.6
2005	31.7
2006	31.4
2007	31.5
2008	31.5
2009	31.7
2010	32
2011	31.8
2012	31.7
2013	31.6
2014	31.6
2015	31.5
2016	31
2017	30.8
2018	30.3
2019	29.5