Year	Number
1971	1358
1972	1681
1973	1920
1974	1906
1975	2034
1976	1880
1977	1900
1978	1954
1979	2051
1980	2240
1981	2289
1982	2348
1984	2378
1986	2549
1987	2922
1988	3064
1989	3057
1991	3120
1992	3293
1998	5962
2012	13804
2016	14791