Year	%
2000	34.2
2001	33.5
2002	34.5
2003	34.1
2004	33.4
2005	34.9
2006	32.8
2007	31.8
2008	30.8
2009	29.1
2010	28.9
2011	28.6
2012	28.3
2013	27.9
2014	28.6
2015	27
2016	26.8
2017	26.4
2018	25.9
2019	25.3