Year	Number
1970	517887
1971	521978
1972	523628
1973	521662
1974	434647
1975	392146
1976	351509
1977	333185
1978	327780
1979	317794
1980	310190
1981	325429
1982	349089
1983	420148
1984	430174
1985	415151
1986	324855
1987	290212
1988	270021
1989	253771
1990	262885
1991	275982
1992	273031
1993	279251
1994	260302
1995	228044
1996	177364
1997	189968
1998	84472
1999	100739
2000	104669
2001	101796
2002	113010
2003	128931
2004	134525
2005	60747
2006	53732
2007	40922
2008	44895
2009	55342
2010	59716
2011	50170
2012	57017
2013	66188
2014	110355
2015	94525
2016	104162
2017	118876
2018	192303