Year	%
2000	27.9
2001	27.5
2002	27
2003	26.6
2004	26
2005	25.4
2006	24.9
2007	24.3
2008	23.7
2009	23.2
2010	22.6
2011	22.2
2012	21.9
2013	21.7
2014	21.5
2015	21.4
2016	21.3
2017	21.2
2018	21.2
2019	21.2