Year	%
2000	23.3
2001	22.8
2002	22.4
2003	21.9
2004	21.5
2005	21.2
2006	20.9
2007	20.6
2008	20.3
2009	20.1
2010	19.8
2011	19.7
2012	19.5
2013	19.4
2014	19.3
2015	19.2
2016	19.2
2017	19.3
2018	19.3
2019	19.4