Year	%
2000	35.8
2001	35.1
2002	34.9
2003	34.7
2004	35.1
2005	34.8
2006	34.5
2007	33.4
2008	32.8
2009	32.3
2010	32.4
2011	32.6
2012	31.6
2013	30.9
2014	31
2015	31
2016	30.9
2017	30.7
2018	30.2
2019	29.2