Year	%
2000	42.5
2001	42.1
2002	41.8
2003	41.5
2004	41.2
2005	40.9
2006	40.5
2007	40.1
2008	39.6
2009	39.2
2010	38.8
2011	38.4
2012	38.2
2013	37.9
2014	37.7
2015	37.5
2016	37.3
2017	37.1
2018	37
2019	36.8