Year	Number
1971	1270
1972	1327
1973	1513
1974	1574
1975	1621
1976	1716
1977	1423
1978	1221
1979	636
1980	270
1981	220
1982	337
1983	650
1984	834
1985	865
1986	962
1987	863
1988	952
1989	1065
1990	1119
1991	1600
1992	2433
1996	2895
1997	3566
1998	7153
1999	8883
2000	9984
2001	10199
2002	12079
2003	14387
2004	16568
2005	19151
2012	11446
2013	15307
2014	18762
2015	14697
2016	16898
2017	14688
2018	11709