Year	%
2000	33.5
2001	32.7
2002	32.3
2003	32.4
2004	32
2005	31.6
2006	31.5
2007	31.2
2008	30.9
2009	30.6
2010	30.3
2011	29.9
2012	29.4
2013	28.9
2014	28.4
2015	28.2
2016	27.9
2017	27.6
2018	27.2
2019	27.5