Year	%
2000	39.4
2001	40.1
2002	40.5
2003	40.1
2004	40.2
2005	40
2006	39.8
2007	39.5
2008	38.9
2009	37.8
2010	37.4
2011	36.8
2012	36.3
2013	36.1
2014	35.7
2015	35.7
2016	36
2017	35.9
2018	36
2019	36.2