| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 16559 | 6258 | 9011 | 1437 | 332 | 135 |
| 1998 | 13259 | 11374 | 2723 | 2736 | 388 | 114 |
| 1999 | 12630 | 8876 | 5846 | 704 | 584 | 109 |
| 2000 | 7030 | 8320 | 3671 | 1414 | 165 | 147 |
| 2001 | 6587 | 4303 | 3056 | 865 | 263 | 61 |
| 2002 | 11732 | 4011 | 1642 | 649 | 136 | 58 |
| 2003 | 3076 | 6818 | 1412 | 416 | 164 | 43 |
| 2004 | 18228 | 1932 | 2318 | 361 | 121 | 67 |
| 2005 | 9118 | 10654 | 586 | 716 | 101 | 54 |
| 2006 | 8744 | 5139 | 3071 | 168 | 179 | 44 |
| 2007 | 2309 | 4057 | 1120 | 601 | 52 | 76 |
| 2008 | 1398 | 927 | 625 | 207 | 136 | 31 |
| 2009 | 4708 | 588 | 180 | 116 | 43 | 25 |
| 2010 | 4392 | 2141 | 175 | 46 | 22 | 12 |
| 2011 | 5291 | 2218 | 592 | 54 | 15 | 9 |
| 2012 | 12207 | 2567 | 483 | 190 | 27 | 10 |
| 2013 | 17443 | 5881 | 897 | 234 | 72 | 18 |
| 2014 | 4970 | 9449 | 1706 | 467 | 133 | 49 |
| 2015 | 3122 | 2163 | 2656 | 957 | 260 | 103 |
| 2016 | 1066 | 1331 | 819 | 986 | 432 | 164 |
| 2017 | 4388 | 601 | 472 | 268 | 285 | 156 |
| 2018 | 476 | 1694 | 128 | 151 | 114 | 165 |
| 2019 | 247 | 190 | 365 | 55 | 32 | 57 |