Year	%
2000	26.4
2001	27.5
2002	27.6
2003	28.9
2004	29.9
2005	30.4
2006	30.6
2007	31.2
2008	30.9
2009	30.5
2010	31
2011	31
2012	31.8
2013	31.7
2014	31.9
2015	32
2016	32
2017	31.6
2018	31.6
2019	31.6