| Year | Count |
|---|---|
| 1951 | 10 |
| 1952 | 45 |
| 1953 | 58 |
| 1954 | 30 |
| 1955 | 111 |
| 1956 | 176 |
| 1957 | 353 |
| 1958 | 297 |
| 1959 | 332 |
| 1960 | 431 |
| 1961 | 455 |
| 1962 | 457 |
| 1963 | 415 |
| 1964 | 453 |
| 1965 | 411 |
| 1966 | 352 |
| 1967 | 286 |
| 1968 | 296 |
| 1969 | 358 |
| 1970 | 369 |
| 1971 | 351 |
| 1972 | 342 |
| 1973 | 241 |
| 1974 | 276 |
| 1975 | 290 |
| 1976 | 287 |
| 1977 | 263 |
| 1978 | 178 |
| 1979 | 233 |
| 1980 | 148 |
| 1981 | 166 |
| 1982 | 121 |
| 1983 | 114 |
| 1984 | 114 |
| 1985 | 214 |
| 1986 | 214 |
| 1987 | 172 |
| 1988 | 174 |
| 1989 | 145 |
| 1990 | 108 |
| 1991 | 80 |
| 1992 | 107 |
| 1993 | 67 |
| 1994 | 57 |
| 1995 | 18 |
| 1996 | 7 |