Year	%
2000	26.7
2001	26.2
2002	25.9
2003	25.8
2004	25.9
2005	25.7
2006	25.6
2007	25.3
2008	26.7
2009	26.5
2010	25
2011	23.5
2012	23.2
2013	22.2
2014	22
2015	22.3
2016	21.7
2017	21.3
2018	20
2019	19.9