| Year | Volume | Number | Holdings | ||
|---|---|---|---|---|---|
| 2012 | 46 | Yes | |||
| 2011 | 45 | Yes | |||
| 2010 | 44 | Yes | |||
| 2009 | 43 | Yes | |||
| 2008 | 42 | Yes | |||
| 2007 | 41 | Yes | |||
| 2006 | 40 | Yes | |||
| 2005 | 39 | Yes | |||
| 2004 | 38 | Yes | |||
| 2003 | 37 | Yes | |||
| 2002 | 36 | Yes | |||
| 2001 | 35 | Yes | |||
| 2000 | 34 | Yes | |||
| 1999 | 33 | Yes | |||
| 1998 | 32 | Yes | |||
| 1997 | 31 | Yes | |||
| 1996 | 30 | Yes | |||
| 1995 | 29 | Yes | |||
| 1994 | 28 | Yes | |||
| 1990-1993 | 24-27 | Yes | |||
| 1971-1989 | 6-23 | Yes | |||
| 1968-1970 | 2-5 | Yes |