Year	%
2000	29.5
2001	28.1
2002	28.2
2003	28
2004	27.7
2005	27.2
2006	26.4
2007	25.8
2008	25.1
2009	24.8
2010	24.6
2011	23.2
2012	22.7
2013	22.2
2014	22.1
2015	22.2
2016	21.8
2017	22.7
2018	22
2019	22