Year	Number
1970	569306
1971	594376
1972	590147
1973	580239
1974	557496
1975	528043
1976	510462
1977	505913
1978	528539
1979	541966
1980	538290
1981	523184
1982	505537
1983	511334
1984	508877
1985	500269
1986	524953
1987	543366
1988	568427
1989	604551
1990	657663
1991	675468
1992	708540
1993	720308
1994	701021
1995	715597
1996	711806
1997	715731
1998	708995
1999	713092
2000	637328
2001	603509
2002	581550
2003	566577
2004	562399
2005	550493
2006	518773
2007	513283
2008	512981
2009	504909
2010	483593
2011	459342
2012	455224
2013	462260
2014	464846
2015	462022
2016	462530
2017	446045
2018	466992