Year	Number
1971	272743
1972	301893
1973	341933
1974	405056
1975	419796
1976	436538
1977	459129
1978	501214
1979	555082
1980	715165
1981	881287
1982	813417
1983	824377
1984	889236
1985	901344
1986	896733
1987	928986
1988	853517
1989	856890
1990	835216
1991	824406
1992	819269
1993	835598
1994	915467
1995	913843
1996	962099
1997	969402
1998	936523
1999	860150
2000	753587
2001	656606
2002	580274
2003	546401
2004	518007
2005	506478
2006	494349
2007	497389
2008	487492
2009	482062
2010	467323
2011	417534
2012	375813
2013	337133
2014	330189
2015	320463
2016	309147
2017	293568