Year	Number
2000	19000
2001	19000
2002	19000
2003	19000
2004	19000
2005	19000
2006	19000
2007	19000
2008	19000
2009	19000
2010	19000
2011	19000
2012	19000
2013	19000
2014	20000
2015	20000
2016	21000
2017	21000
2018	22000
2019	22000
2020	23000