Year	%
2000	22.2
2001	22.5
2002	22.3
2003	22
2004	21.9
2005	21.7
2006	21.3
2007	21
2008	21.1
2009	20.9
2010	20.6
2011	20.5
2012	20.5
2013	20.5
2014	20.5
2015	20.3
2016	20.1
2017	19.9
2018	19.7
2019	19.5