Year	%
2000	27.1
2001	25.9
2002	25.2
2003	24.4
2004	23.7
2005	23
2006	22.2
2007	21.5
2008	20.8
2009	19.9
2010	19.1
2011	18.6
2012	17.9
2013	17.5
2014	17.3
2015	17.3
2016	17.1
2017	17
2018	16.9
2019	16.9