Year	%
2000	25.4
2001	25.1
2002	24.2
2003	23.9
2004	23.1
2005	23
2006	22.4
2007	22.4
2008	21.4
2009	21.1
2010	20.5
2011	19.7
2012	18.8
2013	18.9
2014	18.2
2015	17.5
2016	17
2017	16.5
2018	16
2019	15.5