Year	Number of
2000	2600
2001	2500
2002	2600
2003	2700
2004	2700
2005	2900
2006	2900
2007	3000
2008	2800
2009	3000
2010	3100
2011	3000
2012	3000
2013	2900
2014	3100
2015	3300
2016	3200
2017	3200
2018	3300
2019	2900
2020	3400