Year	%
1990	22.1
1993	22.1
1996	22.4
1999	22.3
2002	22.4
2005	22.3
2008	22.5
2010	22.3
2011	22.3
2012	22.4
2013	22.1
2014	22.3
2015	22.3
2016	22.2
2017	22.1
2018	22.2
2019	22
2020	21.7