Year	Number
1970	324651
1971	335498
1972	329322
1973	326619
1974	312866
1975	312429
1976	310534
1977	298235
1978	310149
1979	319370
1980	325124
1981	314525
1982	297617
1983	300585
1984	301993
1985	298790
1986	309552
1987	307203
1988	321501
1989	332746
1990	367570
1991	381466
1992	397880
1993	403015
1994	392020
1995	395437
1996	398655
1997	397672
1998	391313
1999	391981
2000	353546
2001	339739
2002	334799
2003	330321
2004	321331
2005	320707
2006	306152
2007	304354
2008	305792
2009	305810
2010	293910
2011	279927
2012	285005
2013	280501
2014	285371
2015	279477
2016	292151
2017	286786
2018	288559