Year	Number
1970	9497846
1971	9734877
1972	9679574
1973	9679373
1974	9763309
1975	9686612
1976	9522837
1977	9558473
1978	9642957
1979	9463763
1980	9369622
1981	9466115
1982	9545380
1983	9575509
1984	9432573
1985	9485768
1986	9419317
1987	9297253
1988	9286260
1989	9504850
1990	9280147
1991	9449082
1992	10615968
1993	10677332
1994	10045324
1995	10527108
1996	9826973
1997	9757104
1998	9743750
1999	9158463
2000	8864426
2001	8469381
2002	8148657
2003	7786177
2004	7619805
2005	7612774
2006	7560309
2007	7208121
2008	6694534
2009	6625016
2010	6201409
2011	6411325
2012	6416258
2013	6944384
2014	7164974
2015	7375477
2016	7286890
2017	7143735
2018	7170117