Year	%
2000	22.4
2001	22.4
2002	22
2003	21.7
2004	21.4
2005	20.9
2006	20.5
2007	20.1
2008	19.7
2009	19.1
2010	18.7
2011	18.5
2012	18.2
2013	17.9
2014	17.5
2015	17.3
2016	17
2017	16.6
2018	16.3
2019	16.1