Year	%
1992	32.6
1993	37.2
1996	36
2002	36.5
2004	37
2005	36.7
2006	36.5
2007	36.2
2008	36.5
2009	36.2
2010	36.4
2011	36.2
2012	36.1
2013	36.4
2014	36
2015	35.9
2016	35.8
2017	35.4
2018	35.5
2019	35.7
2020	36.5
2021	36.3