| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 16478 | 6459 | 9035 | 1410 | 339 | 136 |
| 1998 | 13908 | 10837 | 2682 | 2782 | 402 | 113 |
| 1999 | 12462 | 9174 | 5992 | 686 | 593 | 112 |
| 2000 | 7355 | 8425 | 3704 | 1433 | 170 | 145 |
| 2001 | 6802 | 4268 | 3038 | 915 | 259 | 61 |
| 2002 | 11788 | 4106 | 1658 | 621 | 133 | 60 |
| 2003 | 2902 | 6671 | 1462 | 433 | 160 | 40 |
| 2004 | 16518 | 1946 | 2277 | 366 | 118 | 68 |
| 2005 | 8113 | 10031 | 558 | 714 | 95 | 53 |
| 2006 | 8660 | 4878 | 2970 | 161 | 159 | 41 |
| 2007 | 2490 | 3810 | 1030 | 568 | 48 | 74 |
| 2008 | 1358 | 846 | 579 | 180 | 132 | 30 |
| 2009 | 3744 | 475 | 134 | 94 | 36 | 19 |
| 2010 | 3250 | 1498 | 122 | 31 | 15 | 8 |
| 2011 | 3314 | 1545 | 391 | 30 | 9 | 5 |
| 2012 | 8478 | 1646 | 320 | 122 | 17 | 6 |
| 2013 | 11185 | 4237 | 657 | 172 | 46 | 13 |
| 2014 | 4728 | 8166 | 1438 | 406 | 118 | 37 |
| 2015 | 3570 | 2075 | 2752 | 1019 | 272 | 107 |
| 2016 | 1150 | 1431 | 942 | 1093 | 533 | 195 |
| 2017 | 5628 | 752 | 558 | 283 | 299 | 153 |
| 2018 | 563 | 1833 | 114 | 166 | 115 | 153 |
| 2019 | 1385 | 328 | 334 | 32 | 39 | 20 |
| 2020 | 3434 | 641 | 88 | 91 | 5 | 9 |