Year	Number
2000	1700
2001	1600
2002	1800
2003	2000
2004	2400
2005	2400
2006	2300
2007	2500
2008	2600
2009	2600
2010	2500
2011	2300
2012	2000
2013	1800
2014	1700
2015	1700
2016	1500
2017	1600
2018	1500
2019	1500
2020	1500