Year	%
2000	26.6
2001	26.1
2002	25.6
2003	25.1
2004	24.5
2005	23.7
2006	23.1
2007	22.7
2008	22.2
2009	21.9
2010	21.7
2011	21.6
2012	21.5
2013	21.5
2014	21.5
2015	21.4
2016	21.4
2017	21.4
2018	21.5
2019	21.6