Year	Number
1970	6586905
1971	6647635
1972	6589483
1973	6384259
1974	6227530
1975	6246673
1976	6019186
1977	5679113
1978	5495629
1979	4794176
1980	4641058
1981	4208918
1982	4167160
1983	4200044
1984	4315621
1985	4172423
1986	4347153
1987	4373050
1988	4610549
1989	5125599
1990	4940639
1991	4822620
1992	4398536
1993	4257288
1994	4587983
1995	4674691
1996	4427010
1997	4532635
1998	3121836
1999	2262084
2000	1945601
2001	1876697
2002	1814345
2003	1839016
2004	2154583
2005	1490743
2006	2110584
2007	1999459
2008	1308118
2009	1318193
2010	1556300
2011	1582094
2012	1570654
2013	1741015
2014	1852166
2015	1801835
2016	1763680
2017	1675293
2018	2060138