Year	Number
1970	13135
1971	13872
1972	14114
1973	14506
1974	16401
1975	15398
1976	16208
1978	17525
1979	18038
1980	18948
1981	19748
1982	20746
1983	21524
1984	22090
1985	22764
1986	23407
1987	23949
1988	24729
1989	26317
1990	27831
1991	29172
1992	32732
1993	33061
1994	34580
1995	38686
1996	41713
1997	43812
2002	35709
2003	33607
2004	33434
2012	34694