Year	%
2000	28.1
2001	27.7
2002	27.2
2003	27.1
2004	26.8
2005	26.4
2006	26.7
2007	26.5
2008	25.6
2009	25.8
2010	26
2011	25.5
2012	25.3
2013	25
2014	24.3
2015	23.6
2016	22.9
2017	22.3
2018	22
2019	21.7