Year	%
1999	21.2
2001	20.9
2002	20.8
2003	20.8
2004	20.2
2005	20.2
2006	22.1
2007	22.1
2008	22.4
2009	22.4
2010	21.7
2011	22.2
2012	22
2013	22.2
2014	22
2015	21.8
2016	22.8
2017	20.9
2018	20.8
2019	21.7
2020	22.2
2021	21.8
2022	22.4