Year	%
2000	26.4
2001	24.6
2002	25.7
2003	25.6
2004	24.3
2005	25.1
2006	24.4
2007	23.4
2008	22.4
2009	22.3
2010	22.2
2011	19.9
2012	18.9
2013	18.3
2014	17.9
2015	18.6
2016	18
2017	16.2
2018	16.4
2019	15.7