Year	%
2000	31.3
2001	30.7
2002	30.6
2003	30
2004	28.9
2005	29.7
2006	29.4
2007	28.5
2008	26.6
2009	26
2010	25.6
2011	24.4
2012	23.5
2013	23.4
2014	24
2015	24.7
2016	23.9
2017	23.8
2018	22.8
2019	22.6