Year	%
2000	24.4
2001	24
2002	23.8
2003	23.6
2004	23.5
2005	23.4
2006	23.3
2007	23.2
2008	23.1
2009	23
2010	23
2011	23
2012	22.9
2013	22.9
2014	22.9
2015	22.8
2016	22.7
2017	22.5
2018	22.5
2019	22.5