Year	%
2000	37.1
2001	34.9
2002	32.6
2003	31.1
2004	30.3
2005	28.9
2006	28.1
2007	27.6
2008	27.1
2009	27
2010	26.3
2011	26.1
2012	26.3
2013	25.6
2014	24.8
2015	23.7
2016	23.7
2017	23.1
2018	22.9
2019	23