Year	years
1998	7
1999	7
2000	7
2001	8
2002	8
2003	8
2004	9
2005	8.5
2006	9
2007	9
2008	9
2009	9
2010	8.5
2011	8.5
2012	8.5
2013	9
2014	9
2015	9
2016	9
2017	9
2018	9
2019	9
2020	9
2021	9
2022	9
2023	9