Year	%
2000	36.8
2001	36.4
2002	35.8
2003	35.4
2004	34.7
2005	33.8
2006	33
2007	32
2008	30.9
2009	29.9
2010	29.2
2011	28.6
2012	28.3
2013	28.1
2014	28.1
2015	28.3
2016	28.4
2017	28.5
2018	28.8
2019	29