Year	%
2000	27.6
2001	27
2002	26.5
2003	26
2004	25.5
2005	24.9
2006	24.4
2007	23.9
2008	23.4
2009	23
2010	22.7
2011	22.4
2012	22.1
2013	21.9
2014	21.8
2015	21.6
2016	21.5
2017	21.4
2018	21.3
2019	21.4