Year	%
2000	32.9
2001	32.1
2002	31.8
2003	30.8
2004	30.9
2005	30.8
2006	30.7
2007	30.3
2008	30.4
2009	30
2010	29.6
2011	29.3
2012	28.9
2013	28.6
2014	28.3
2015	28.1
2016	27.7
2017	27.4
2018	27.2
2019	26.8