Year	%
2000	36.7
2001	34.1
2002	31.8
2003	29.5
2004	27.5
2005	26
2006	25
2007	24.2
2008	23.4
2009	22.5
2010	22
2011	21.5
2012	21.2
2013	20.8
2014	20.8
2015	20.6
2016	20.4
2017	20.3
2018	20.3
2019	20.2