Year	%
2000	34.7
2001	34
2002	34.1
2003	34.1
2004	34.6
2005	35.3
2006	33.8
2007	33.9
2008	33.5
2009	30.8
2010	29.7
2011	28.3
2012	28.2
2013	27.4
2014	27.7
2015	26.2
2016	26
2017	25.1
2018	26.1
2019	25.5