Year	%
2000	38.4
2001	38.2
2002	37.8
2003	37.4
2004	37.2
2005	36.7
2006	35.3
2007	33.7
2008	33.3
2009	31.7
2010	31.3
2011	31
2012	31
2013	30.7
2014	30.2
2015	29.7
2016	28.9
2017	28.5
2018	28.2
2019	27