| Year | Count |
|---|---|
| 1971 | 5 |
| 1972 | 6 |
| 1977 | 7 |
| 1978 | 5 |
| 1979 | 11 |
| 1980 | 13 |
| 1981 | 6 |
| 1982 | 11 |
| 1983 | 7 |
| 1984 | 7 |
| 1985 | 6 |
| 1986 | 6 |
| 1987 | 10 |
| 1988 | 8 |
| 1989 | 6 |
| 1990 | 8 |
| 1991 | 5 |
| 1992 | 5 |
| 1997 | 5 |
| 1998 | 6 |
| 2002 | 5 |
| 2007 | 6 |
| 2009 | 5 |
| 2012 | 9 |
| 2013 | 9 |
| 2015 | 10 |
| 2016 | 28 |
| 2017 | 22 |
| 2018 | 36 |
| 2019 | 32 |
| 2020 | 12 |
| 2021 | 11 |
| 2022 | 10 |
| 2023 | 11 |
| 2024 | 6 |