Year	%
2000	25.3
2001	24.7
2002	24
2003	23.2
2004	22.6
2005	22.3
2006	21.9
2007	21.9
2008	22
2009	21.4
2010	21.3
2011	21.2
2012	21.1
2013	21
2014	21.5
2015	21.4
2016	21.2
2017	21
2018	20.7
2019	20.6