Year	%
2000	27.7
2001	27.3
2002	27
2003	26.9
2004	26.7
2005	26.5
2006	26.1
2007	25.7
2008	25.2
2009	24.5
2010	24.1
2011	24
2012	23.7
2013	23.4
2014	23.2
2015	23
2016	22.8
2017	22.7
2018	22.6
2019	22.6