Year	%
2000	32
2001	31.5
2002	30.9
2003	30.7
2004	30.5
2005	29.9
2006	29.7
2007	29.3
2008	28.3
2009	28.2
2010	28.3
2011	28
2012	27.9
2013	27.4
2014	26.6
2015	25.8
2016	25
2017	24.4
2018	24
2019	23.6