| Table 2. Estimated stock numbers. | ||||||
| Year\Age | 1 | 2 | 3 | 4 | 5 | 6+ |
| 1997 | 17424 | 6220 | 9177 | 1416 | 320 | 132 |
| 1998 | 13679 | 11853 | 2766 | 2686 | 369 | 111 |
| 1999 | 12709 | 9130 | 5901 | 702 | 571 | 104 |
| 2000 | 7084 | 8441 | 3783 | 1408 | 160 | 144 |
| 2001 | 6463 | 4381 | 3148 | 851 | 262 | 59 |
| 2002 | 11753 | 3964 | 1672 | 680 | 139 | 58 |
| 2003 | 2935 | 6882 | 1393 | 413 | 166 | 44 |
| 2004 | 16757 | 1828 | 2297 | 351 | 117 | 65 |
| 2005 | 7826 | 9648 | 544 | 650 | 94 | 50 |
| 2006 | 7311 | 4322 | 2615 | 145 | 161 | 38 |
| 2007 | 1922 | 3320 | 907 | 491 | 42 | 62 |
| 2008 | 1211 | 752 | 511 | 168 | 108 | 25 |
| 2009 | 4087 | 497 | 136 | 93 | 34 | 22 |
| 2010 | 3500 | 1803 | 136 | 36 | 18 | 10 |
| 2011 | 4281 | 1737 | 479 | 44 | 11 | 7 |
| 2012 | 9364 | 2077 | 400 | 158 | 21 | 8 |
| 2013 | 12016 | 4480 | 693 | 184 | 62 | 14 |
| 2014 | 3856 | 6494 | 1328 | 361 | 102 | 41 |
| 2015 | 2720 | 1739 | 2024 | 737 | 207 | 82 |
| 2016 | 919 | 1209 | 664 | 801 | 348 | 137 |
| 2017 | 3751 | 499 | 431 | 224 | 237 | 138 |
| 2018 | 675 | 1535 | 106 | 149 | 78 | 115 |
| 2019 | 962 | 324 | 356 | 38 | 34 | 28 |
| 2020 | 3033 | 415 | 79 | 119 | 9 | 14 |