Year	%
2000	29.9
2001	29.7
2002	29.4
2003	29.2
2004	28.7
2005	28.6
2006	28.6
2007	28.4
2008	28.3
2009	28.3
2010	28.1
2011	27.9
2012	27.8
2013	27.8
2014	27.8
2015	27.8
2016	27.7
2017	27.7
2018	27.8
2019	28