Year	%
1992	22.9
1993	23.2
1995	30.4
1996	27.6
2002	23.2
2003	23.3
2004	23.1
2005	23.2
2006	24.1
2007	22
2008	21.9
2009	21.2
2010	21
2011	20.7
2012	20.8
2013	21.1
2014	20.6
2015	21.6
2016	21.2
2017	21.7
2018	22
2019	22.3
2020	21.8