| Year | Count |
|---|---|
| 1950 | 10 |
| 1956 | 125 |
| 1957 | 153 |
| 1958 | 97 |
| 1959 | 118 |
| 1960 | 96 |
| 1961 | 44 |
| 1962 | 65 |
| 1963 | 76 |
| 1964 | 70 |
| 1965 | 42 |
| 1966 | 21 |
| 1967 | 19 |
| 1968 | 10 |
| 1969 | 11 |
| 1970 | 41 |
| 1971 | 59 |
| 1972 | 87 |
| 1973 | 80 |
| 1974 | 76 |
| 1975 | 78 |
| 1976 | 92 |
| 1977 | 145 |
| 1978 | 97 |
| 1979 | 81 |
| 1980 | 105 |
| 1981 | 766 |
| 1982 | 2,332 |
| 1983 | 3,008 |
| 1984 | 4,279 |
| 1985 | 3,675 |
| 1986 | 1,995 |
| 1987 | 1,408 |
| 1988 | 1,059 |
| 1989 | 881 |
| 1990 | 548 |
| 1991 | 497 |
| 1992 | 330 |
| 1993 | 210 |
| 1994 | 162 |
| 1995 | 112 |
| 1996 | 66 |
| 1997 | 35 |
| 1998 | 6 |
| 1999 | 6 |
| 2000 | 11 |
| 2001 | 24 |
| 2002 | 8 |
| 2003 | 10 |
| 2004 | 10 |
| 2006 | 5 |
| 2007 | 9 |
| 2009 | 15 |