Year	%
2000	24.3
2001	23.7
2002	22.8
2003	22.7
2004	22.4
2005	23.2
2006	22.4
2007	22
2008	21.8
2009	22.3
2010	22.2
2011	20.5
2012	19.9
2013	19.9
2014	19.5
2015	19.2
2016	18.8
2017	18.3
2018	17.9
2019	17.5