Year	Number
1976	2915753
1977	3108629
1978	3301145
1979	3379506
1980	3703199
1981	3846737
1985	3797621
1986	4022858
1987	4182113
1988	4217754
1989	3881316
1990	3440358
1991	3235992
1992	3253100
1993	3383800
1994	3869900
1995	4500800
1996	5332400
1997	5995300
1998	6642350
1999	7222645
2000	7743132
2001	8117967
2002	8588509
2003	8955994
2004	9228306
2005	9472815
2006	9474861
2007	9329737
2008	8928507
2009	8467012
2010	8100135
2011	7803327
2012	7681611
2013	7545159
2014	7463517
2015	7537413
2016	7563776
2017	7712699
2018	7882203