Year	years
1999	4
2000	4
2001	4
2002	4
2003	4
2004	4
2005	4
2006	4
2007	4
2008	4
2009	4
2010	4
2011	4
2012	4
2013	5
2014	5
2015	5
2016	5
2017	5
2018	5.5
2019	5.5
2020	5.5
2021	5.5
2022	6
2023	6