Year	%
2000	28.5
2001	27.8
2002	28.6
2003	28.3
2004	27.9
2005	28.9
2006	27.1
2007	26.2
2008	25.3
2009	23.8
2010	23.6
2011	23.1
2012	22.8
2013	22.6
2014	23.1
2015	22.2
2016	22.1
2017	21.9
2018	21.6
2019	21.2