Year	Number
1990	18
1991	18
1992	16
1993	15
1994	15
1995	14
1996	13
1997	13
1998	14
1999	14
2000	14
2001	16
2002	16
2003	17
2004	17
2005	18
2006	19
2007	20
2008	20
2009	20
2010	21
2011	21
2012	21
2013	21
2014	21
2015	22
2016	23
2017	23
2018	23
2019	23
2020	23
2021	23
2022	21