Year	Number
1972	1930345
1973	2255750
1974	2366148
1975	2442842
1976	2164328
1977	2213068
1978	2638543
1979	2323571
1980	2632904
1981	2381346
1983	2930757
1984	3083643
1985	3097871
1986	3104893
1987	3238993
1988	3308347
1989	3377368
1990	3562194
1998	9031080
1999	9806527
2000	10223908
2001	10566996
2002	10897971
2003	10924016
2004	10186996
2005	9916904
2006	10031776
2007	10190592
2008	9692260
2009	10539656
2010	10961531
2011	11178900
2012	11758695
2013	12884519
2015	13964691
2016	15160895
2017	14702156
2018	15112531