Year	%
2000	27.7
2001	27.3
2002	27
2003	26.8
2004	26.8
2005	26.1
2006	24.9
2007	24.3
2008	24.1
2009	23.9
2010	23.8
2011	23.6
2012	23.3
2013	22.8
2014	22.1
2015	21.7
2016	21.4
2017	20.8
2018	20.4
2019	20.2