Year	%
2000	35.8
2001	35.2
2002	34.6
2003	33.9
2004	33.3
2005	32.7
2006	32
2007	31.3
2008	30.6
2009	29.9
2010	29.4
2011	29
2012	28.6
2013	28.3
2014	28.1
2015	28
2016	27.9
2017	27.9
2018	27.8
2019	27.7