Year	%
1997	25.4
1998	24
1999	23.6
2000	24.2
2001	23.8
2002	24.2
2003	22.8
2004	23.9
2005	23.9
2006	24.2
2007	24.6
2008	23.3
2009	22.3
2010	21.6
2011	21.7
2012	21.5
2013	20.9
2014	20.5
2015	19.5
2016	20.6
2017	20
2018	19.3
2019	18.7
2020	19.8
2021	16.1
2022	16.4