Year	%
1982	36
1992	33.9
2000	33.4
2002	31.7
2006	33.9
2007	34.3
2008	33.8
2009	32.9
2010	32.6
2011	31.7
2012	31.6
2013	32.5
2014	32.5
2015	32.3
2016	33
2017	32.7
2018	33.1
2019	34
2020	33.7