Year	%
2000	29.9
2001	29.8
2002	29.9
2003	30
2004	29.8
2005	29.7
2006	29.6
2007	29.5
2008	29.3
2009	28.8
2010	28.5
2011	28.1
2012	28
2013	28.1
2014	27.8
2015	27.1
2016	26.7
2017	26.4
2018	26.2
2019	26