Year	%
1984	21.7
1987	21.5
1990	21.2
1993	21
1996	20.7
1998	21.3
1999	21
2000	21.5
2001	21.3
2002	21
2003	21.4
2004	21.4
2005	21.2
2006	21.2
2007	21.3
2008	21.3
2009	21.1
2010	21.6
2011	20.7
2012	20.5
2013	20.5
2014	20.6
2015	20.5
2016	21.5
2017	21.8
2018	21.9
2019	21.9
2020	21.8
2021	21.5
2022	21
2023	20.6