Year	%
2000	54.2
2001	52.3
2002	51.4
2003	52.5
2004	50.3
2005	50.1
2006	48.4
2007	48.1
2008	44.8
2009	42.4
2010	42.4
2011	41
2012	39.7
2013	37.4
2014	36
2015	35.2
2016	34.1
2017	33.2
2018	32
2019	31.1