Year	Number
1971	72371
1972	67614
1973	57451
1974	43414
1975	40583
1976	39361
1977	44992
1978	51923
1979	61050
1980	75847
1981	61320
1982	58750
1983	50882
1984	51428
1985	52768
1986	61422
1987	81999
1988	74639
1989	78318
1990	79307
1991	79864
1992	93406
1993	106628
1994	109049
1995	96439
1996	98684
1997	91400
1998	41753
1999	37277
2000	28561
2001	36497
2002	35107
2003	34796
2004	36916
2005	44251
2006	48002
2007	48791
2010	40958
2011	38660
2012	36452
2013	40327
2014	49076
2015	43505