Year	%
2000	42.6
2001	42.4
2002	41.7
2003	41.1
2004	40.3
2005	39.6
2006	39
2007	38.7
2008	38.3
2009	37.9
2010	37.6
2011	37.4
2012	37.4
2013	37.3
2014	37.2
2015	37.2
2016	37.2
2017	37.1
2018	37.1
2019	37