Year	%
1992	15.6
1993	13.9
1996	14.6
2002	14.4
2004	14.3
2005	14.5
2006	14.5
2007	14.6
2008	14.6
2009	14.6
2010	14.5
2011	14.6
2012	14.5
2013	14.5
2014	14.6
2015	14.7
2016	14.7
2017	14.7
2018	14.7
2019	14.5
2020	14.4
2021	14.4