Year	Number
2000	1200
2001	1100
2002	1200
2003	1100
2004	1200
2005	1200
2006	1300
2007	1300
2008	1400
2009	1500
2010	1400
2011	1400
2012	1500
2013	1400
2014	1500
2015	1400
2016	1600
2017	1600
2018	1700
2019	1700
2020	1900