Year	%
2000	34.2
2001	34.7
2002	35.4
2003	35.1
2004	33.9
2005	33.7
2006	32.9
2007	32.2
2008	31.9
2009	32
2010	31.3
2011	29.9
2012	29.8
2013	29
2014	29.4
2015	29.5
2016	29.3
2017	29.3
2018	29.6
2019	28.6