Year	%
2003	37.2
2004	33.6
2005	33.4
2006	33.7
2007	31.2
2008	31.9
2009	31.4
2010	32
2011	32.5
2012	32.9
2013	35.1
2014	34.6
2015	32.7
2016	31.2
2017	30.4
2018	30.3
2019	30.8
2020	30.7
2021	31.8