Year	%
2000	22.7
2001	22.9
2002	22.6
2003	22.3
2004	22.1
2005	21.9
2006	21.5
2007	21.2
2008	21.3
2009	21
2010	20.7
2011	20.4
2012	20.4
2013	20.2
2014	20.2
2015	19.9
2016	19.7
2017	19.5
2018	19.3
2019	19.1