Year	%
1992	19.9
1996	22.8
1999	24.5
2000	22.7
2001	22.7
2002	21.7
2003	20.8
2004	20.4
2005	20.5
2008	23.3
2009	22.2
2010	22
2011	21.5
2012	21.9
2013	21.8
2014	21.7
2015	21.1
2016	20.7
2017	20.2
2018	20.4
2019	21.2
2020	22.2
2021	21.7
2022	21.7