Year	%
2000	34.6
2001	35.4
2002	35.5
2003	35.4
2004	36.1
2005	37.7
2006	38.6
2007	39.2
2008	36.5
2009	35.7
2010	35
2011	35
2012	33.9
2013	32.8
2014	31.7
2015	32.8
2016	31.6
2017	29.3
2018	29.4
2019	28.4