Year	%
2000	27.6
2001	27
2002	26.5
2003	26.1
2004	25.6
2005	25
2006	24.5
2007	24
2008	23.4
2009	22.8
2010	22.3
2011	21.9
2012	21.4
2013	21.1
2014	20.8
2015	20.6
2016	20.4
2017	20.3
2018	20.2
2019	20.2