Year	%
2000	29.6
2001	29.3
2002	30.1
2003	29.1
2004	28.7
2005	28.4
2006	28.5
2007	29.4
2008	31.1
2009	31.4
2010	32.1
2011	32.4
2012	32.1
2013	32.2
2014	32.3
2015	32.6
2016	32.2
2017	31
2018	29.7
2019	29.8