Year	Number
1970	17785
1971	19581
1972	22861
1973	25318
1974	27046
1975	29762
1976	31455
1977	33127
1978	34390
1979	36242
1980	38690
1981	39701
1982	41471
1984	47124
1986	49974
1987	53752
1988	55046
1989	57676
1990	55797
1991	58249
1992	58226
1993	65406
1994	70392
1995	68818
1998	116972
2012	349038
2016	463600