| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ | 
| 1997 | 15303 | 6990 | 10341 | 1567 | 413 | 181 | 
| 1998 | 13945 | 9947 | 2595 | 2734 | 402 | 109 | 
| 1999 | 14209 | 9362 | 6043 | 651 | 581 | 109 | 
| 2000 | 9045 | 7502 | 3749 | 1426 | 173 | 143 | 
| 2001 | 5359 | 4976 | 3165 | 951 | 257 | 62 | 
| 2002 | 9589 | 3013 | 1313 | 587 | 127 | 59 | 
| 2003 | 3439 | 5391 | 1317 | 370 | 131 | 32 | 
| 2004 | 13400 | 2524 | 2042 | 348 | 110 | 65 | 
| 2005 | 8942 | 7066 | 781 | 729 | 92 | 52 | 
| 2006 | 9590 | 4868 | 2943 | 191 | 168 | 45 | 
| 2007 | 3776 | 3461 | 730 | 669 | 62 | 99 | 
| 2008 | 1869 | 1008 | 688 | 149 | 129 | 29 | 
| 2009 | 5420 | 758 | 185 | 123 | 49 | 23 | 
| 2010 | 5459 | 3074 | 208 | 56 | 28 | 14 | 
| 2011 | 6318 | 3351 | 754 | 59 | 19 | 10 | 
| 2012 | 11398 | 2625 | 443 | 206 | 31 | 10 | 
| 2013 | 21161 | 5728 | 998 | 158 | 47 | 16 | 
| 2014 | 6186 | 15051 | 1641 | 495 | 103 | 10 | 
| 2015 | 5478 | 2501 | 3633 | 694 | 223 | 58 |