Year	%
2000	31.4
2001	30.4
2002	29.4
2003	28.8
2004	28.4
2005	27.6
2006	27.8
2007	27.9
2008	27.6
2009	27.7
2010	27.6
2011	26.4
2012	25.4
2013	24.6
2014	24.3
2015	24
2016	23.7
2017	23.4
2018	22.9
2019	22.6