Year	%
2000	41.7
2001	41
2002	40.9
2003	40.3
2004	39.9
2005	39.4
2006	39.7
2007	39.4
2008	39.1
2009	39.5
2010	39.4
2011	39.1
2012	38.6
2013	38.5
2014	38.2
2015	38.1
2016	37.4
2017	37.1
2018	36.5
2019	36