Year	%
2000	31
2001	30.6
2002	30.1
2003	29.7
2004	29.4
2005	29.1
2006	28.7
2007	28.4
2008	28.3
2009	27.9
2010	27.4
2011	27.2
2012	27.1
2013	26.9
2014	26.7
2015	26.6
2016	26.8
2017	27.1
2018	27.4
2019	27.6