Year	%
2000	30.8
2001	29.9
2002	28.8
2003	27.5
2004	26
2005	24.3
2006	22.1
2007	20.3
2008	18.9
2009	18.2
2010	17.9
2011	17.8
2012	17.6
2013	17.4
2014	17.2
2015	16.8
2016	16.4
2017	15.9
2018	15.6
2019	15.4