Year	%
2000	43.9
2001	44.1
2002	43.6
2003	42.9
2004	42.5
2005	41.8
2006	41.3
2007	40.7
2008	40
2009	39.1
2010	38.3
2011	37.5
2012	36.8
2013	36.2
2014	35.7
2015	35.4
2016	35.1
2017	35
2018	34.7
2019	34.4