Year	Number
1970	331411
1971	341986
1972	337191
1973	331554
1974	316069
1975	304849
1976	298371
1977	286849
1978	298858
1979	306904
1980	311918
1981	304921
1982	296176
1983	297029
1984	294910
1985	292523
1986	306042
1987	311205
1988	324757
1989	336817
1990	370321
1991	389365
1992	406934
1993	415612
1994	403499
1995	409983
1996	410497
1997	406552
1998	401503
1999	407507
2000	366863
2001	344156
2002	335700
2003	324458
2004	316807
2005	308983
2006	292696
2007	288412
2008	283124
2009	282321
2010	269712
2011	258634
2012	255942
2013	249858
2014	249757
2015	245019
2016	263088
2017	258457
2018	258459