Year	%
2000	28.6
2001	27.5
2002	26.5
2003	26
2004	25.4
2005	24.6
2006	24.7
2007	24.9
2008	24.6
2009	24.5
2010	24.3
2011	23.1
2012	22.1
2013	21.4
2014	21.1
2015	20.9
2016	20.7
2017	20.7
2018	20.4
2019	20