Year	Number
1970	2745892
1971	2364147
1972	2551420
1973	2745731
1974	2904604
1975	3101532
1976	3769403
1977	4181509
1978	4223429
1979	6101337
1980	6393212
1981	6637452
1982	6899099
1983	7076720
1984	7410727
1985	5381010
1986	7574137
1987	7511147
1988	7414566
1989	7201630
1990	7010442
1991	6758000
1992	6616265
1993	6359226
1994	6032990
1995	5793481
1996	5574226
1997	5087014
1998	5628622
1999	4097040
2000	4329458
2001	4052655
2002	3842592
2003	4131462
2004	4436599
2005	4469687
2006	4756715
2007	4980467
2008	5346878
2009	5439195
2010	5695925
2011	5716290
2012	6034224
2013	6892079
2014	7006116
2015	7238156
2016	7447188
2017	7519091
2018	7517874