Year	Number
1998	20354140
1999	19947472
2000	19187648
2001	18969812
2002	19320812
2003	18516564
2004	17069074
2005	16730329
2006	18323262
2007	16441981
2008	18492652
2009	18092196
2010	18900000
2011	18900000
2012	18900000
2013	18200000
2014	17900000
2015	19200000
2016	18400000
2017	19000000
2018	17900000