Year	Number
1970	6640384
1971	6672908
1972	6596738
1973	6398335
1974	6263087
1975	6318856
1976	6101995
1977	5755285
1978	5572702
1979	4870057
1980	4715415
1981	4204622
1982	4182412
1983	4261597
1984	4415141
1985	4257155
1986	4474178
1987	4540050
1988	4799600
1989	5298517
1990	5090163
1991	4964257
1992	4592372
1993	4455271
1994	4817270
1995	4905095
1996	4674975
1997	5268871
1998	3312205
1999	2432393
2000	2127355
2001	2071232
2002	2019087
2003	2046275
2004	2269546
2005	1581992
2006	2176903
2007	2030693
2008	1332676
2009	1388587
2010	1607530
2011	1640828
2012	1628509
2013	1812257
2014	1919395
2015	1858206
2016	1834948
2017	1741840
2018	2187793