| Year | Total |
|---|---|
| 1992 | 873 |
| 1993 | 793 |
| 1994 | 712 |
| 1995 | 684 |
| 1996 | 757 |
| 1997 | 659 |
| 1998 | 495 |
| 1999 | 317 |
| 2000 | 253 |
| 2001 | 214 |
| 2002 | 163 |
| 2003 | 135 |
| 2004 | 140 |
| 2005 | 93 |
| 2006 | 100 |
| 2007 | 74 |
| 2008 | 68 |
| 2009 | 110 |
| 2010** | 105 |
** Provisional data
Source: 1992 - 2010 Labbase 2
Last reviewed: 30 December 2011