| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ | 
| 1997 | 15021 | 6384 | 9006 | 1417 | 336 | 136 | 
| 1998 | 13778 | 10702 | 2642 | 2782 | 398 | 114 | 
| 1999 | 10600 | 9045 | 5986 | 688 | 590 | 111 | 
| 2000 | 8346 | 8192 | 3649 | 1428 | 169 | 146 | 
| 2001 | 7607 | 4249 | 2971 | 901 | 261 | 62 | 
| 2002 | 12116 | 4180 | 1649 | 637 | 138 | 61 | 
| 2003 | 3628 | 6950 | 1520 | 447 | 172 | 43 | 
| 2004 | 17457 | 2252 | 2547 | 409 | 135 | 78 | 
| 2005 | 9171 | 11491 | 639 | 817 | 111 | 61 | 
| 2006 | 11023 | 5849 | 3546 | 195 | 197 | 50 | 
| 2007 | 3463 | 4872 | 1338 | 739 | 62 | 95 | 
| 2008 | 1807 | 1192 | 820 | 258 | 182 | 42 | 
| 2009 | 5491 | 731 | 230 | 157 | 59 | 31 | 
| 2010 | 5027 | 2578 | 220 | 57 | 28 | 15 | 
| 2011 | 6376 | 2707 | 704 | 61 | 18 | 10 | 
| 2012 | 14848 | 2880 | 548 | 223 | 33 | 12 | 
| 2013 | 19076 | 6958 | 1124 | 277 | 79 | 23 | 
| 2014 | 7544 | 11717 | 2285 | 591 | 168 | 56 | 
| 2015 | 4050 | 2646 | 4705 | 1427 | 379 | 151 | 
| 2016 | 576 | 1708 | 1159 | 2669 | 778 | 297 |