| Year | Count |
|---|---|
| 1956 | 6 |
| 1964 | 5 |
| 1969 | 5 |
| 1970 | 7 |
| 1971 | 8 |
| 1972 | 6 |
| 1974 | 7 |
| 1975 | 9 |
| 1976 | 11 |
| 1978 | 9 |
| 1979 | 6 |
| 1980 | 5 |
| 1981 | 11 |
| 1983 | 8 |
| 1986 | 5 |
| 1987 | 8 |
| 1988 | 6 |
| 1989 | 6 |
| 1990 | 7 |
| 1991 | 8 |
| 1996 | 7 |
| 1997 | 6 |
| 2000 | 12 |
| 2001 | 6 |
| 2002 | 9 |
| 2003 | 5 |
| 2005 | 5 |
| 2006 | 5 |
| 2007 | 12 |
| 2008 | 7 |
| 2010 | 23 |
| 2013 | 12 |
| 2015 | 12 |
| 2017 | 6 |