| Year | Count |
|---|---|
| 1953 | 5 |
| 1954 | 7 |
| 1956 | 6 |
| 1957 | 6 |
| 1958 | 12 |
| 1959 | 6 |
| 1960 | 10 |
| 1961 | 10 |
| 1962 | 12 |
| 1963 | 6 |
| 1964 | 12 |
| 1965 | 10 |
| 1966 | 15 |
| 1967 | 6 |
| 1968 | 14 |
| 1969 | 11 |
| 1970 | 10 |
| 1971 | 9 |
| 1973 | 13 |
| 1974 | 7 |
| 1975 | 6 |
| 1976 | 5 |
| 1978 | 7 |
| 1981 | 6 |
| 1982 | 9 |
| 1983 | 9 |
| 1987 | 8 |
| 1989 | 9 |
| 1990 | 5 |
| 1991 | 7 |
| 1992 | 6 |
| 1995 | 5 |
| 1997 | 5 |
| 2006 | 8 |
| 2007 | 5 |
| 2008 | 12 |
| 2009 | 10 |
| 2010 | 6 |
| 2012 | 13 |
| 2013 | 5 |
| 2014 | 6 |
| 2015 | 9 |
| 2016 | 16 |
| 2017 | 18 |
| 2018 | 20 |
| 2021 | 6 |