Year	%
2000	30.1
2001	29.7
2002	29.5
2003	29.4
2004	29.2
2005	28.6
2006	28.2
2007	27.4
2008	26.4
2009	25.5
2010	24.6
2011	23.8
2012	23
2013	22.5
2014	22.2
2015	21.8
2016	21.5
2017	20.9
2018	20.6
2019	20.2