Year	%
2000	33.4
2001	33.1
2002	32.6
2003	32.2
2004	31.6
2005	31
2006	30.2
2007	29.3
2008	28.3
2009	27.3
2010	26.4
2011	25.5
2012	24.8
2013	24.1
2014	23.6
2015	23
2016	22.6
2017	22.3
2018	22
2019	21.8