| Year | # of birds | # + EEE | # + SLE |
| 1988 | 790 | 9 | 1 |
| 1989 | na | 10 | 9 |
| 1990 | 711 | 0 | 258 |
| 1991 | 866 | 7 | 15 |
| 1992 | 928 | 13 | 0 |
| 1993 | 860 | 0 | 76 |
| 1994 | 876 | 4 | 16 |
| 1995 | 1089 | 5 | 3 |
| 1996 | 1031 | 12 | 0 |
| 1997 | 991 | 2 | 176 |
| 1998 | 1089 | 1 | 60 |
| 1999 | 1029 | 9 | 63 |
| average (1988-98) | 5.7 | 55.0 | |
| median (1988-98) | 5.0 | 15.0 |