Year	%
2000	25.6
2001	25.5
2002	25.2
2003	24.9
2004	24.5
2005	24.5
2006	24
2007	23.8
2008	22.7
2009	22.4
2010	22.2
2011	21.9
2012	21.9
2013	21.7
2014	21.6
2015	21.3
2016	21
2017	20.7
2018	20.1
2019	19.8