Year	%
2000	22.9
2001	23.3
2002	23
2003	19.7
2004	19.8
2005	21.7
2006	21.5
2007	22.3
2008	21.9
2009	21.7
2010	21.5
2011	21
2012	21.3
2013	21
2014	21.1
2015	20.8
2016	20.6
2017	20.7
2018	20.5
2019	20.4