Year	Number
2000	22000
2001	21000
2002	21000
2003	20000
2004	20000
2005	19000
2006	19000
2007	19000
2008	19000
2009	19000
2010	19000
2011	19000
2012	19000
2013	19000
2014	19000
2015	19000
2016	19000
2017	19000
2018	19000
2019	20000
2020	20000