| Year | Volume | Number | Holdings | ||
|---|---|---|---|---|---|
| 2002 | 22 | 3 | Yes | ||
| 2002 | 22 | 2 | Yes | ||
| 2002 | 22 | 1 | Yes | ||
| 2001 | 21 | 1 -3 | Yes | ||
| 2000 | 20 | 1 -3 | Yes | ||
| 1999 | 19 | 1 -3 | Yes | ||
| 1998 | 18 | 1 -3 | Yes | ||
| 1997 | 17 | 1 -3 | Yes | ||
| 1996 | 16 | 1 -3 | Yes | ||
| 1995 | 15 | 1 -3 | Yes | ||
| 1994 | 14 | 1 -4 | Yes | ||
| 1993 | 13 | 1 -4 | Yes | ||
| 1992 | 12 | 1 -3 | Yes | ||
| 1991 | 11 | 1 -4 | Yes | ||
| 1990 | 10 | 1 -4 | Yes | ||
| 1989 | 9 | 1 -4 | Yes | ||
| 1988 | 8 | 1 -4 | Yes |